Colorectal cancer: symptoms, screening, treatment, prognosis. Colorectal cancer - risk factors Used medications such as

Colorectal cancer is a general name for cancers that affect the rectum and large intestine. Colorectal cancer is one of the most common cancers and ranks second in terms of incidence, second only to lung cancer. The number of patients is growing every year and for every 100 thousand people in the world there are 30 patients with colorectal cancer.

Colorectal cancer (CRC) is a subtype of tumors that are malignant, predominantly located on the epithelium of the large intestine and. According to medical statistics, the tumor is localized in the rectum mainly in men and in the large intestine in women. This type of tumor localization does not exceed 10% of all those diagnosed with colorectal cancer, and most often they are adenocarcinomas.

Colorectal cancer statistics show that in developed countries people are much more likely to encounter this type of disease than other types of oncology. The highest incidence of the disease is found in Australia, North America, New Zealand and the CIS countries, and the lowest in Africa and South Asia. Such geographical differences are determined by the level of exposure to colorectal cancer risk factors - limited diet, bad habits, environment.

In Russia, colorectal cancer is considered one of the most popular diseases. Among males and females, colon cancer ranks 3rd after and and after and. A high mortality rate in the first year of life after diagnosis of the disease is considered a dangerous call. This is characterized by the fact that when patients first visit a doctor, they have an incurable form of cancer that cannot be cured by surgery.

Colorectal cancer: causes

The main factors for the appearance of a tumor in the intestine are:

genetic predisposition;
eating large amounts of red meat;
drinking alcohol;
smoking;
passive lifestyle;
lack of fresh fruits and vegetables, cereals.

Each of these causes leads to colorectal cancer. If people eat a diet that does not contain fiber but contains animal protein, fat and refined carbohydrates, the risk of developing a tumor in the intestines is high. Excess weight doubles the risk of disease. Regular drinking and smoking can be factors that increase the risk of colon polyposis and colon cancer.

Colorectal cancer: symptoms

Colorectal cancer manifests itself slowly, and it takes some time for the first symptoms to be detected. If you suspect you have colorectal cancer, the symptoms depend on the area where the tumor is located, the type and stage of spread, and complications. A distinctive feature of this disease is that it appears too late, when treatment, alas, does not bring positive results. The patient does not see or feel the tumor. And only when it reaches an impressive size and begins to grow into nearby organs or gives rise to metastases, the patient feels a burning sensation, pain, and the presence of blood in the stool.

The first section of the large intestine is large, has a thin wall and contains fluid, so blockage of the intestinal space occurs at the last moment. Most often, patients suffer from heaviness in the stomach, disorders, pain in the liver and pancreas. Fatigue increases, weakness appears in the morning due to anemia. Sometimes the tumor is large, allowing doctors to feel it through the abdominal wall before other symptoms occur.

With rectal cancer, the main cause is bleeding when trying to go to the toilet. There may be a false sensation of bowel movement. There is pain during defecation. In many situations, even before the onset of symptoms, patients can find the causes of metastatic damage - the appearance of a tumor in other organs.

At an early stage, the patient feels anemia, weakness, and sometimes the temperature rises. Such signs imply the manifestation of many diseases; their occurrence is a reason to consult a doctor.

Stages of colorectal cancer

There are 4 stages of colorectal cancer development and stage 0:

Stages of development of cancer in the intestine

early stage or stage 0 - the neoplasm does not extend beyond its plate. The survival rate at this stage is 99%;
Stage 1 colorectal cancer - the tumor is located on the intestinal wall and does not spread further beyond the submucosal or muscular layer. The survival rate is quite high and is 90%;
Stage 2 - the neoplasm extends beyond the intestinal wall and connects to the visceral peritoneum or neighboring organs. Other organs are not affected. The survival rate is 60% to 70%;
Stage 3 - cancer cells penetrate the lymph nodes. Survival statistics are deteriorating and range from 20% to 55%;
Stage 4 colorectal cancer - cancer cells penetrate other organs of the body and lymph nodes. Having this stage of the disease, the probability of survival is 5%.

At an early stage, the patient notices blood at the time of defecation, pain appears in the abdomen, often in the lateral sections or in the anus. Such pain can be bursting and aching. Disappears after defecation. The pain also subsides after using a warm heating pad and medications that speed up metabolism.

At the last stage, tumor poisoning appears, which differs in the stages of the disease, the patient’s health status, the size of the tumor, and the presence of a corresponding disorder. The patient loses weight, mental retardation appears, the temperature rises, and sweating increases. The patient is exposed to various infectious diseases.

To determine the stage of the disease, you need to do a colorectal cancer test. This is usually a general blood test - it is needed to detect anemia, which is related to prolonged bleeding from a tumor in the intestine.

Types of colorectal cancer:

. This is the most common form of bowel cancer. It can be diagnosed in 80% of cases. Sprouts from glandular tissue. This type of cancer occurs in people over 50 years of age. The lower the level of differentiation, the more dangerous the disease and the worse the prognosis.
Signet ring cell appearance. This form occurs in 4% of people. Cancer got its name because of its appearance. If a tumor cell is examined under the device, a lumen will be visible in the center of the cell, and a narrow rim with a nucleus at the edges. It seems to resemble a ring with a large stone. This form of bowel cancer is fatal. Patients die in the first few years.
Solid bowel cancer. It is extremely rare and grows from glandular tissue. This form consists of poorly differentiated cells that look like plates.
Skyr- This type of cancer is rare. It contains a minimal number of cells and a lot of intercellular fluid.
Squamous cell carcinoma. This is the third type of intestinal tumor, which is prone to early metastases. It can be found in the lower intestine near the anus.
Melanoma. The tumor arises from pigment cells called melanocytes. Located in the anal area.

Colorectal cancer screening and diagnosis

If the patient has the listed complaints or is at high risk for developing colorectal cancer, the most effective method of early diagnosis is colonoscopy - a special examination of the mucous membrane, rectum, and colon.

Colonoscopy is performed in special clinics or medical centers. Before the procedure, the patient is placed on the bed on his side. The doctor gives the patient anesthesia and uses a special colonoscope - a long and thin tube with a small light bulb and camera at the end. During this study, all polyps are eliminated or pieces are taken for histology.

Before prescribing surgical treatment or other methods of therapy, you need to undergo a full examination, which includes:

Fecal occult blood test.
Flexible sigmoidoscopy.
Fibercolonoscopy.
Irrigoscopy - a special substance is injected using an enema so that the extent of the lesion can be seen using an x-ray.

Once cancer has been detected, patients need to undergo a CT scan of the abdomen and chest to detect metastases. You will also need to undergo laboratory testing to assess the level of anemia.

In 80% of patients with this diagnosis, a high increase in serum carcinoembryonic antigen is expected. In the future, it is useful to monitor and diagnose cancer recurrence. It is also important to get tested for colorectal cancer screening.

For many people over 50, screening for colorectal cancer is considered a colonoscopy. If there are polyps or other neoplasms in the colon, then you need to be examined every year.

The most important and simplest way to diagnose intestinal cancer is a digital examination of the intestine. The biggest and most common mistake is ignoring this method. Even if hemorrhoids are suspected, a digital examination is required, with which an accurate diagnosis can be made.

This study is carried out with the patient lying down with the knees pulled down. If it is impossible to palpate the tumor, the patient is examined in a squatting position.

An X-ray examination can reveal the general picture of colon cancer. After analyzing the clinical signs and obtaining stool and blood samples, a final diagnosis is made. To exclude metastasis to the liver, ultrasound is prescribed.

Treatment of colorectal cancer

Surgery for colorectal cancer

In most cases, colorectal cancer is treated with surgery.

The extent of the operation depends on the stage of cancer development:

At the early stage of the disease, when the tumor is clearly localized, only the affected intestinal fragment with the surrounding tissue and regional lymph nodes is removed.
A widespread tumor localized in the lower part requires more radical intervention. It is necessary to remove the rectum along with the sphincter. A sigmostoma is placed on the anterior abdominal wall - a direct connection between the sigmoid colon and the surface of the skin. In the future, stool will be removed through this stoma.
It is also possible to perform a more gentle operation - sphincter-preserving resection. During the operation, the rectum is removed, the sphincter remains in place, and the sigmoid colon is sutured to it. This type of operation is more convenient for the patient in the future, but despite this, the anatomical structure does not always allow the overlying section to be brought in without tension on the tissue.
If the cancer is at stage 4 and is complicated by intestinal obstruction, the operation is performed in several stages. Initially, it is necessary to restore the movement of food masses through the intestines; for this, the patient is given a colostomy - an anastomosis between the colon and the surface of the skin. Afterwards, an operation is performed to remove the tumor in the manner described above.

Radiation therapy treatment

Radiation therapy greatly reduces the possibility of disease recurrence and increases the maximum effectiveness of cancer treatment. Depending on the situation, your doctor may prescribe a procedure before surgery to stop tumor growth, at the time of surgery to eliminate the risk of tumor cells multiplying, or after surgery to reduce the recurrence of the disease.

Chemotherapy treatment

Chemotherapy can increase the maximum effectiveness of treatment. The doctor determines the optimal content and quantity of chemotherapy drugs.

Medicines used include:

Irinotecan;
Leucovorin;
Tegafur.

Treatment of metastatic colorectal cancer

If the patient is diagnosed with metastatic colorectal cancer, survival is up to 1 year. Metastatic refers to a group of diseases that cannot be cured.

In this case, complex treatment is prescribed, which includes:

removal of part of the intestine;
elimination of metastases;
a course is assigned;
a course is assigned;
prescribed - a way to stimulate the immune system, which helps fight cancer cells with the help of drugs.

Features of nutrition and diet

During treatment for colorectal cancer, the patient must adjust his lifestyle and diet. Proper nutrition is an additional positive factor that will help maintain the patient’s normal condition during therapy.

Low-fat cottage cheese, yogurt, kefir, sour cream in small quantities.
White bread crackers.
Vegetables - carrots, tomatoes, cauliflower and broccoli, various greens, spinach, zucchini.
Fruits, namely: apricots, plums, apples.
Porridge - barley, oatmeal, buckwheat, pearl barley.
Eggs in small quantities (1 per day).
seafood.

It is also necessary to introduce anti-carcinogenic foods and vitamins into the diet, namely:

vitamin A, which is found in liver and fish oil;
vitamin E, which is found in vegetable oil and nuts;
berries and fruits with vitamin C;
bran, cereals, seafood, liver - selenium;
sea fish and algae - iodine;
pumpkin, carrots, tomatoes, apricots - carotenoids;
berries, citrus fruits, apples, beets - flavonoids.

Foods that should be excluded from the patient’s diet:

fatty, fried, smoked foods;
confectionery, sweets, sugar;
spices and marinades;
sweet soda;
alcoholic drinks;
strong coffee;
legumes, cabbage, turnips, cucumbers;
grape;
sausages;
whole milk;
black bread;
semi-finished products, stewed meat and canned fish.

Metastases in colorectal cancer

In most cases, colorectal cancer metastasizes to the liver. This happens due to the special features of hemodynamics in this organ. The main job of the liver in the body is detoxification, so this organ has a special system of active blood flow: blood enters the liver not only through the aorta, but also through the portal vein. In a minute, up to 1.5 liters of blood flows through the liver, and more than half of it penetrates through the portal vein from the intestines. Then, in the sinusoids of the liver, blood circulation slows down, venous and arterial blood meet each other, penetrating into the central hepatic vein and the inferior vena cava. This creates a good environment for the emergence of cancer cells.

Metastases of colorectal cancer enter the lymph nodes of the mesentery and the intestinal pelvic tissue; then the lymph nodes along the aorta are exposed. Hematogenous metastases appear in the liver. Metastasis to the bones was also observed. If the tumor is deep in the anus, the inguinal lymph nodes are affected, and then surgery involves the removal of these lymph nodes.

Symptoms of liver metastases:

the patient feels constant weakness, performance decreases;
weight loss. Cachexia syndrome develops;
loss of appetite, vomiting;
the skin becomes sallow in color and spider veins form on the skin;
the patient feels heaviness in the stomach, bursting pain;
high temperature, development of tachycardia;
the external veins of the abdomen dilate;
jaundice may appear;
the intestines are not working well.

Danger of metastasis to the liver

Metastases interfere with the normal functioning of the liver, which, in addition to poisoning, produces many complex biochemical reactions, including the production of glucose to supply the body with it. Metastases in the liver reduce overall health, severe pain appears, which can only be relieved with the help of painkillers.

Prevention of colorectal cancer

People who have been diagnosed with polyps, intestinal polyposis, and chronic inflammation of the rectum are required to be observed by proctologists once a year. The main prevention of colorectal cancer is diet and proper and healthy nutrition. It is necessary to reduce the amount of meat and use gentle methods to combat constipation: enemas, herbal preparations.

Colorectal cancer: prognosis

People who are diagnosed with colorectal cancer have a very dismal prognosis. The 5-year survival rate with lymphoid tissue hyperplasia is 70% and 56% of those. The 5-year survival rates are the same for both. If a person has stage 1 cancer, the survival rate is 80%, stage 2 is 60%, stage 3 is 40%, and in the final stage the survival rate is less than 5%. The statistics present rather disappointing figures. This is due to late diagnosis of the disease. Therefore, be vigilant about your health, visit qualified doctors more often for preventive purposes, do not abuse alcohol and smoking, and do not ignore the causes of cancer, as your health is in your hands.

Informative video on the topic: colorectal cancer or colon cancer

Risk assessment for hereditary colorectal cancer.

A key step in stratifying patients into risk groups is documenting an accurate family history, which, in the absence of a diagnosis of familial adenomatous polyposis (FAP) or hereditary nonpolyposis colorectal cancer (HNPCC), allows empirical risk assessment. Focus should be placed on the site and age of diagnosis of all cancers in family members, as well as the presence of associated conditions, such as colorectal adenomas. This can be time-consuming, especially when information needs to be verified. Few surgeons are able to devote the necessary time to this or know how to do it satisfactorily, so clinics. Familial cancer clinics or familial cancer registries play an important role in assessing the risk of incidence (level of evidence: 2).

A complete life history should also be collected, paying particular attention to the following facts:

– presence of symptoms (eg rectal bleeding, change in bowel habits) that should be investigated as usual;
– previous colon polyps;
previous colon cancer;
– cancer of another localization;
– other risk factors for colorectal cancer: inflammatory bowel disease (IBD), ureterosigmostoma, acromegaly; These conditions are not discussed further in the chapter, but may serve as a basis for monitoring the condition of the large intestine.

Family history has many limitations, especially in small families. Other difficulties arise from incorrect information, loss of contact between family members, early death before cancer develops and the fact that the patient was adopted. Common sense is required not to try to cover the emerging wide range of complex pedigrees with equally complex recommendations. If the family is between risk groups (for example, one first-degree relative with bowel cancer on one side at age 55, and the other on the same side as a second-degree relative at age 50), it would be safer to run the family as if they were in a high-risk group. Despite this, some families will be at high risk simply due to the random accumulation of true sporadic cancers, while some, especially small, families with HNPCC will be at low or intermediate risk. In addition, even in families affected by autosomal dominant conditions, 50% of family members will not have an inherited causative mutated gene and therefore will not have an increased risk of developing bowel cancer.

It should also be taken into account that family history “evolves”, so that a patient's risk group classification may change if a family member later develops a tumor. It is important that patients are informed about this, especially if they are at low or moderate risk and therefore are not regularly screened.

Low risk group

This group includes most of the population. People in this group are characterized by:

– there is no personal history of intestinal cancer; there is no confirmation of a family history of colon cancer; or
– no first-degree relatives (for example, parents, siblings or children) with bowel cancer; or
– one first-degree relative with bowel cancer diagnosed at age 45 or older.

Medium risk group

Patients fall into this category if they have:

– one first-degree relative with bowel cancer diagnosed before the age of 45 years (without the high-risk features described below); or
– two first-degree relatives with bowel cancer diagnosed at any age (without the high-risk features described below).

High risk group

– family members with established FAP or other polyposis syndrome;
– family members with established hereditary colorectal cancer;
– pedigree indicates autosomal dominantly inherited colorectal (or other HNPCC-associated) cancer; Various other criteria are also used, for example: 3 or more first or second degree relatives (grandparents, uncles/aunts, nieces/nephews) with colon cancer on one side; 2 or more first or second degree relatives with bowel cancer on one side of the family and one or more with the following high-risk features:

– multiple intestinal cancer in one;
– diagnosis before 45 years of age;
– a relative with endometrial or other HNPCC-associated cancer.

The diagnosis of polyposis syndrome is relatively simple, since in each case there is an easily recognizable phenotype. Diagnosing hereditary colorectal cancer is much more difficult because there is no easily recognizable phenotype, but only the possibility of cancer occurring.

Low risk group

The risk of developing bowel cancer even in patients in this group may be 2 times higher than the average risk. although this trend is observed only in patients after 60 years of age. There is no convincing evidence to support invasive surveillance methods in this group. It is important to explain to these patients that they have an average or slightly higher than average risk of developing colorectal cancer, but this risk is no more significant than the disadvantages of colonoscopy. They should be aware of the symptoms of colorectal cancer and the importance of notifying them if another family member develops the cancer. In addition, population screening. is likely to be introduced into practice in the UK in the foreseeable future, and patients in this at-risk group should be encouraged to take part.

Medium risk group

There is a three to sixfold increase in comparative risk in this group of patients. but only slight benefit from observation is possible.

Part of the explanation for this is that the incidence of colorectal cancer is low in young people but increases significantly in older people. Therefore, even 50-year-olds who have a sixfold increase in comparative risk due to their family history are less likely to develop colorectal cancer in the next 10 years than 60-year-olds with an average risk.

Current recommendations are that patients in this risk group should be offered a colonoscopy at age 35–40 (or at the time of visit if older) and repeated at age 55. If a polyp is detected, follow-up is modified accordingly. The use of flexible sigmoidoscopy is unjustified, since neoplasms in patients with a family history are often located more proximally; If it is impossible to reach the cecum, irrigoscopy or CT colography should be performed.

These patients should also be informed about the symptoms of colorectal cancer, the importance of reporting changes in family history, and that they should participate in population-based screening if introduced into practice.

High risk group

Patients in this group have a one in two chance of inheriting a high risk of developing bowel cancer and should be referred to a clinical genetics service. Polyposis syndromes are usually diagnosed by phenotype, which can be confirmed by genetic testing. Diagnostic difficulties may arise, especially in cases where adenomatous polyps are insufficient to diagnose FAP. This may occur in FAP with an unclear phenotype or in hereditary colorectal cancer. A careful search for extracolonic features, correction of immunohistochemical errors and assessment of microsatellite instability (MSI) in tumor tissue, as well as identification of germline mutations, may sometimes be helpful. Despite this, the diagnosis remains uncertain in some families. In these circumstances, family members should be offered close monitoring.

HEREDITARY NONPOLYPOSUS COLORECTAL CANCER

Hereditary nonpolyposis colorectal cancer accounts for approximately 2% of colorectal cancers and is the most common of the two major hereditary colorectal cancer syndromes. Hereditary colorectal cancer was formerly known as Lynch syndrome and is inherited in an autosomal dominant pattern. It was originally called "familial cancer syndrome" and then the name was changed to hereditary colorectal nonpolyposis cancer to distinguish it from polyposis syndromes and to note the absence of the large number of colorectal adenomas found in FAP. However, adenomatous polyps are considered a sign of hereditary colorectal cancer. The terms Lynch syndrome I and II were proposed in 1984 to describe patients with predominant colorectal cancer at a young age (Lynch I) and those with colorectal and extracolic cancer (Lynch II).

Clinical signs of hereditary colorectal cancer

Hereditary nonpolyposis colorectal cancer is characterized by early manifestation of colorectal tumors, the average age of diagnosis is 45 years (compared to the general population - 65 years). These tumors have precise distinctive pathological features: a tendency to affect the proximal part of the colon, often multiple tumors (synchronous and metachronous). They tend to be mucus-forming, have a low level of differentiation and a “signet-ring” appearance with significant infiltration of lymphocytes and accumulation of lymphoid tissue at their edges. Combined cancer tumors and their incidence are presented in Table. 2-1. The prognosis for these tumors is better than for similar tumors that occur sporadically

Table 2-1. Cancers associated with hereditary nonpolyposis colorectal cancer

Genetics of colorectal cancer

Hereditary colorectal cancer is caused by mutations in the base pairing error correction (BER) genes, which correct errors in base pair matching during DNA (deoxyribonucleic acid) replication or initiation of apoptosis when DNA damage cannot be repaired. The following UOS genes have been identified, mutations in which may be associated with HNPCC: hMLHl, hMSH2, hMSH6, hPMSl, hPMS2 and hMSH3. UCO genes are tumor suppressor genes: Patients with hereditary colorectal cancer inherit a defective copy from one parent, and tumorigenesis is triggered when the only normal gene in a cell becomes mutated or lost due to external causes such that DNA base pairing errors no longer exist in that cell are being corrected. When UOSO is defective, mutations accumulate among other genes, which leads to the formation of a tumor.

Defective UOSO also leads to NMS, a characteristic feature of tumors in hereditary colorectal cancer. Microsatellites are areas where short DNA sequences (up to 5 nucleotides) are repeated. There are a huge number of such sequences in the human genome, most of them are located in the non-coding part of the DNA. Base pairing errors that occur during DNA replication are normally repaired by UOCO proteins. In tumors deficient in these proteins, this mechanism becomes ineffective, and microsatellites mutate, leading to changes in the number of sequence repeats (NSRs). It is typical for such tumors that more than half of all microsatellites exhibit this phenomenon.

NMS is present in approximately 25% of colorectal cancer cases. Some of them are associated with hereditary colorectal cancer and occur due to the inheritance of UOSO mutations. The majority, however, occur in older patients and are thought to arise from inactivation of UCO genes by methylation over time, and age-related changes in the colonic epithelium are not heritable.

Although the dominant disorder is based on the UOSO mutation, there is convincing evidence for the presence of other causes acting on the expression of HNKR in the population. Thus, a comparative study of Korean and Danish families with hMLHl mutations showed that stomach and pancreatic cancer occurred more often in Koreans, and endometrial cancer less often than in Danes. This means that either these Korean families had modified genes common in the general population (which carry a high risk of gastric cancer) or that the Korean population was exposed to environmental factors that interact with the mutations responsible for HNPCC-associated cancers.

Diagnosis of hereditary colorectal cancer

There have been many conflicting "criteria" over the years. The International Joint Group on NKGD (JJGKG), established in 1989, proposed the Amsterdam criteria in 1990 (Box 2-1). They were not limited to just a diagnostic definition and became a way to identify families in which hereditary colorectal cancer is likely to be hidden. The purpose of formulating criteria is to allow genetic research to target a clearly defined group that is most likely to produce a positive result. While families who fully meet these criteria have hereditary colorectal cancer, many other affected families will not encounter the obligatory conditions. The Amsterdam criteria were modified by the IHNCR in 1999 (Block 2-2) to include HNPCC-associated non-colorectal cancers (Amsterdam Criteria II), so that the diagnosis of hereditary colorectal cancer can be made using a set of these criteria. However, some families affected by hereditary colorectal cancer will not qualify.

Block 2-1. Hereditary nonpolyposis colorectal cancer: Amsterdam criteria I

– At least 3 relatives with colorectal cancer, one of whom must be first degree relative to the other two
– Must have affected at least 2 consecutive generations At least 1 case of colorectal cancer must have been diagnosed before age 50
– SAP should be eliminated

Block 2-2. Hereditary nonpolyposis colorectal cancer: Amsterdam criteria II

– At least 3 relatives with HNPCC-related cancer (colorectal, endometrial, small bowel, ureteral, renal pelvis), one of whom must be first degree related to the other two
– At least 2 successive generations must be affected
– At least 1 case of cancer must have been diagnosed before age 50
– SAP should be eliminated
– Tumors must be verified upon examination by a pathologist

Genetic research is expensive and time-consuming. The circumstances under which it is performed vary among centers, but in general, patients with HNPCC-related cancer from families that fully meet the Amsterdam criteria I and II should undergo the study. In families in which the risk of hereditary colorectal cancer is not clearly high, but clinical suspicion remains, analysis of tumor tissue can provide additional useful information.

Tumor tissue analysis

A reference panel of 5 microsatellite markers is used to detect NMJ; if 2 markers show instability, the tumor is designated as “high NMS.” Only 25% of colorectal cancer cases have high NMS, but only a small proportion will in patients with hereditary colorectal cancer. The value of the NMS study is that hereditary colorectal cancer arises from the UCO mutation and therefore virtually all tumors arising from hereditary colorectal cancer will have a high NMS. The Bethesda guidelines (box 2-3) indicate whether tumor tissue obtained from a patient should be tested for the presence of NMS. Their goal is to provide precise recommendations that will include almost all cases of HNPCC-associated colorectal cancer, as well as many "sporadic cancers", and to use the NMC test to exclude those patients who do not have a high NMC and are unlikely to have cancer caused by NNKR. Patients identified as having high NMS can then be evaluated using immunohistochemistry and genetic testing. Using this approach, approximately 95% of cases of patients with colorectal cancer due to HNPCC are identified.

Block 2-3. Bethesda criteria for determining the need for testing for microsatellite instability in tumor tissue obtained from a patient with colorectal cancer

– Patients with colorectal cancer diagnosed at age 50
– Patients with multiple colorectal or other HNPCC-associated tumors that occurred either simultaneously (synchronous) or later (metachronous)
– Patients with colorectal cancer diagnosed before the age of 60 years whose tumor has microscopic features of NMS
– Patients who have one or more first-degree relatives diagnosed at age 50 years or younger with an HNPCC-related tumor
– Patients with two or more first- or second-degree relatives diagnosed with an HNPCC-related tumor at any age

NMC testing is expensive, requires DNA extraction, and is a relatively inaccessible technology. A simpler approach that can be used routinely on all colorectal tumor specimens is to use a standard immunohistochemical method for detecting UCO proteins. Immunohistochemistry results, if reported in standard histopathologic form, will also serve to remind surgeons of each possibility of hereditary colorectal cancer and the importance of genetic testing. The results should be interpreted with caution because abnormal UCO protein, which stains normally but is not functional, may be present in hereditary colorectal cancer.

Genetic study of hereditary colorectal cancer

The decision to perform cell line genetic testing on a blood sample obtained from at-risk or ill individuals is based on patient, family, and tumor characteristics. This cautious approach is currently justified on the basis of cost, with genetic testing of the first family member's UOS genes (detecting the mutation) currently costing around £1,000. Logistic models for estimating the probability of mutation of the UOCO gene, based on the Amsterdam criteria I, at the average age of diagnosis of colorectal cancer in the family and in the presence of endometrial cancer, were developed to develop a molecular analysis strategy. Where the probability of detecting a mutation is greater than 20%, cell line testing is recommended; where less than 20%, NMS analysis is recommended based on the cost-effectiveness principle. Once a mutation is detected in one family member, testing other family members for carriage of the pathological gene (predictive testing) is more direct and allows relatives who do not have the mutation to be excluded from further observation.

As with other syndromes described in this chapter, the study should be carried out only after appropriate explanations to the patient and obtaining informed consent from him. The consent process should include written information containing a frank discussion of the benefits and risks (eg, employment, insurance) of genetic testing. Multidisciplinary clinics where consultations with various specialists are available are ideal. However, not every patient will agree to genetic testing. Significant predictors of patients' understanding of the study included increased risk perception, greater belief in ability to cope with bad news, more frequent thoughts about cancer, and having had at least one colonoscopy.

Genetic testing of a cell line may have multiple outcomes (box 2-4), and the results should be communicated to a multidisciplinary clinic where consultation is available.

Block 2-4. Outcomes of genetic research in hereditary non-polyposis colorectal cancer

Study of family members at increased risk (predictive study): if positive, observation and/or other treatment (eg, surgery); if the result is negative, no observation is required

No mutation detected

Keep all family members at increased risk under observation (the test currently has a sensitivity of approximately 80%)

There are reasonable difficulties in interpreting the results (nonsense mutations, genetic heterogeneity, limited availability of accurate chemical analysis). Indiscriminate genetic testing for cancer risk leads to errors and side effects. which provides additional support for the need for meaningful system design that includes genetic testing for cancer susceptibility. Failure to detect a mutation may occur due to various factors: in some cases, mutations in regulatory genes may occur rather than in the UOS genes themselves; other as yet unidentified genes may be involved; it may be technically impossible to identify the existing mutation; family history may actually be sporadic tumors. When this occurs, screening of high-risk family members should continue.

Surveillance of hereditary colorectal cancer

The risk of extracolon cancer depends on which gene is mutated, being approximately 50% for hMSH2 mutation carriers and approximately 10% for hMLHl mutation carriers. Screening for extracolonic cancer is available, but there is currently little strong evidence of its benefit. Recommendations vary from center to center, but in general, surveillance is recommended where there is a family history of rare cancer. Box 2-5 shows surveillance methods for extracolic tumors.

Block 2-5. Observation of extracolonic tumors in hereditary non-polyposis colorectal cancer

Annual transvaginal ultrasound ± color Doppler ultrasound + endometrial biopsy

Annual CA125 measurement and clinical examination (pelvis and abdomen)
Endoscopic examination of the upper gastrointestinal tract every 2 years

Annual urinalysis/cytology
Annual ultrasound of the abdominal cavity/urinary tract, pelvis, pancreas
Annual liver function tests, CA19-9, carcinoembryonic antigen

Prevention of hereditary colorectal cancer

Colectomy can be subtotal with ileorectal anastomosis (IRA) or as a variation of IRP. Using a decision analysis model, we show a significant increase in life expectancy in hereditary colorectal cancer mutation carriers when any intervention is undertaken. Benefits were defined as 13.5 years for follow-up, 15.6 years for proctocolectomy, and 15.3 years for subtotal colectomy compared with no intervention. Regulation of quality of life showed that observation leads to the most quality-regulated life expectancy. This study provided only a mathematically based indication of the benefit: individual circumstances need to be incorporated into the decision-making process when making recommendations.

Treatment of hereditary colorectal cancer

The risk of metachronous colon tumors is 45% (level of evidence: 2). For patients with colon tumors, colectomy with ileorectal anastomosis is a prophylactic element, in which the colon is completely removed and there are no additional complications of proctectomy. Proctocolectomy (with or without ileoanal reconstruction, which depends on the height of the tumor, the age and general condition of the patient, and the condition of the anal sphincter) is the preferred method for patients with rectal cancer.

Drug therapy for hereditary colorectal cancer

In vitro studies of colorectal cancer using cells deficient in UOS genes have shown that NMS is reduced in cells exposed to nonsteroidal anti-inflammatory drugs (NSAIDs). This provides some theoretical basis for the PAC 2 (Colorectal Adenoma/Carcinoma Prevention Program 2) study currently underway in patients with hereditary colorectal cancer, using aspirin and resistant starch as chemopreventive agents. To date, however, there is no convincing evidence to support the use of any drug in the treatment of hereditary colorectal cancer. The benefit of cytotoxic chemotherapy for cancer in the setting of hereditary colorectal cancer remains controversial and the available data are conflicting. Some drugs (especially fluorouracil) act by damaging DNA, leading to apoptosis. UOCO proteins are thought to be partially involved in signaling the presence of irreversible DNA damage and the initiation of apoptosis, which is absent in these tumors.

Development in the future

Screening, surveillance, and treatment may be more individualized in the future due to a better understanding of genotype-phenotype interactions. Gene therapy for hereditary colorectal cancer (as well as for other congenital colorectal cancer syndromes) remains the focus of research. Hereditary colorectal cancer may still undergo changes in nomenclature, and the name may be replaced by “hereditary nucleotide mismatch repair deficiency syndrome” (HNVRR). Until colorectal surgeons and other physicians become familiar with the molecular basis of diagnosis, inherited nucleotide mismatch repair deficiency syndrome will not be an easy-to-understand or clinically clear acronym. If anyone's lack of understanding of this condition is applied to hereditary bowel cancer in general, it will also result in poorer patient survival, which currently carries the risk of medicolegal implications.

The term “colorectal cancer” hides a very dangerous disease, most often affecting the epithelial tissues lining the walls of the rectum.

The localization of malignant neoplasms is indicated by the very name of the disease, formed by merging the Latin designations for these parts of the large intestine: “colon” - colon, and “rectum” - rectum.

Concept of illness

Malignant neoplasms, designated by the term “colorectal cancer,” represent a fairly large and very heterogeneous group of tumors, characterized by different localization, shape and histological structure of tissues.

. This is the main (at least 50% of cases) route of metastasis of cancer cells, due to the peculiarities of the blood supply to the liver, which receives most of the blood from the portal vein, fed by the internal organs. A patient with liver metastases experiences a high degree of exhaustion, constant nausea and vomiting, severe jaundice and itching of the skin, the presence of (fluid accumulation in the abdomen) and severe abdominal pain.
The peritoneum is a film of connective tissue that covers the surface of all internal organs and lines the walls of the abdominal cavity. Cancer cells that have grown through the walls of the affected intestine first form foci in separate areas of the peritoneum, and having captured it entirely, they spread to the neighboring organs covered by it.
. A patient with metastases in the lungs suffers from shortness of breath, pain in the lungs, and a constant cough accompanied by hemoptysis.

Screening and diagnosis

A colorectal cancer screening test is performed using:

Digital examination of the rectum. This simplest method allows you to detect up to 70% of carcinomas localized in it.
. The use of a rigid sigmoidoscope allows you to examine the condition of the walls of the rectum and the distal sigmoid colon. If suspicious neoplasms are detected, a tissue biopsy is performed.
Irrigoscopy is a procedure consisting of performing a barium enema and pumping air to expand the lumen of the intestine being examined. X-rays taken during this examination can detect polyps and malignant tumors.
Fibercolonoscopy. The use of a flexible fiber colonoscope equipped with a fiber optical system allows you to examine the condition of the large intestine along its entire length. Being the most accurate and expensive research technique, fibrocolonoscopy is performed at the final stage of patient examination.

In addition to the above examination methods, which are considered basic, a number of methods are used in relation to the patient:

angiography;
laparoscopy;
presence test .

Tumor markers

In case of colorectal cancer, two tumor markers are most often found in the blood serum of a sick person:

, which has prognostic significance. A level greater than 37 ng/ml indicates that the risk of death in operated patients with this result is 4 times higher than in patients with a lower or negative result.
(carcinoembryonic antigen). As a rule, an increased level of CEA is observed when the disease is already advanced, and a high level is observed when the tumor has metastasized to the liver.

Stages and treatment options

The location of a stage I colorectal tumor, which occupies a smaller part of the circumference of the affected intestine, is its mucous membrane and submucosal layer. There are no metastases to the lymph nodes.
Stage IIa malignant neoplasm occupies approximately half of the intestinal lumen and is limited to its walls. Regional lymph nodes are not affected.
A tumor that has reached stage IIb and has grown through the entire thickness of the intestinal wall begins to metastasize to the nearest regional lymph nodes.
A stage III malignant tumor occupies more than half of the intestinal lumen and gives multiple metastases to.
A stage IV tumor is called metastatic colorectal cancer and is characterized by significant size and distant metastasis.

Carry out:

By surgical intervention, which consists of removing the malignant neoplasm (during the operation of colectomy or hemicolectomy) and the affected lymph nodes (the operation of lymphadenectomy). Operations can be open, that is, performed by cutting the abdominal wall, and laparoscopic, performed through micro-incisions (using manipulators and miniature video systems).
The method is the use of medications that can stop the division of cancer cells. Chemotherapy for colorectal cancer can precede surgery and is often used in the postoperative period. If the tumor is inoperable, chemotherapy remains the only treatment that can improve the patient's quality of life.
A method that uses the power of x-rays to destroy cancer cells. Radiotherapy is used both as an independent method of treatment and in combination with chemotherapy.

Forecast

The prognosis for colorectal cancer is directly dependent on the stage at which the malignant neoplasm was detected.

Treatment of tumors caught at the very beginning of formation results in a five-year survival rate of 95% of patients.
Stage III colorectal cancer that has metastasized to the lymph nodes is characterized by a five-year survival rate of 45% of patients.
A malignant intestinal tumor removed at stage IV gives less than 5% of patients a chance of survival.

Prevention

Primary prevention of colorectal cancer includes:

A balanced diet containing plenty of fruits, vegetables and foods high in dietary fiber.
Limited consumption of red meat and animal fats.
Quitting drinking alcohol and smoking.
Active lifestyle.
Body weight control.

Secondary prevention, aimed at early detection, consists of performing a screening examination of patients at risk and in the age category over fifty years.

The following video will tell you where to start treating metastatic colorectal cancer:

coloproctologist, oncologist surgeon, Ph.D.

What is colorectal cancer

“Colorectal cancer” is a collective term for cancer (tumor) of various parts of the colon and rectum. Among many oncological diseases, this pathology remains the least illuminated and the most covered in myths and fears of patients, but, nevertheless, modern early diagnostic capabilities give reason to consider CRC to be ~95% preventable cancer.

Statistics from developed countries indicate a steady increase in newly diagnosed cases of colon and rectal cancer compared to malignant tumors of any other location except lung cancer. Globally, incidence varies widely, with the highest rates in Australia and New Zealand, Europe and North America, and the lowest in Africa and Central and South Asia. Such geographical differences are apparently determined by the degree of influence of risk factors for colorectal cancer - diet, bad habits, environmental factors against the background of genetically determined susceptibility to the development of this type of cancer.

In Russia, colorectal cancer occupies one of the leading positions. Among men diagnosed with malignant neoplasms, colorectal cancer is in 3rd place after lung and stomach cancer, and in women, respectively, after breast cancer and skin cancer. An alarming fact is the high mortality rate in the 1st year of life after diagnosis, due to the fact that when patients first visit a doctor, more than 70% of patients with colon cancer and more than 60% of patients already have advanced forms of cancer (stages III-IV). with rectal cancer, with about 40% of patients undergoing surgical treatment.

In the United States, there are approximately 140,000 new cases and approximately 50,000 deaths due to colorectal cancer each year. Surprisingly, the United States has seen a slow but steady downward trend in the incidence of colorectal cancer, and survival rates for colorectal cancer are among the highest in the world. Reporting data from the US National Cancer Institute shows that 61% of patients with this diagnosis exceeded the five-year survival rate.

In the United States and many other Western countries, improved outcomes have been achieved, in particular, by timely detection and removal of colon polyps, early diagnosis of colorectal cancer and more effective treatment. Unfortunately, in many countries with limited resources and poor health care infrastructure, especially in Central and South America and Eastern Europe, mortality from colorectal cancer continues to rise.

Risk factors for colorectal cancer

Colorectal cancer most often develops as a degeneration of adenomatous (glandular) polyps.

Although genetic predisposition significantly increases the risk of developing CRC, the majority of cases are (in other words - unpredictable, episodic) rather than familial: approximately 80-95% of cases are sporadic versus 5-20% having a hereditary cause. But among all other human cancers, CRC shows the greatest association with familial incidence. Research into the molecular mechanisms of colorectal cancer development has revealed a number of genetic disorders, most of which are inherited in an autosomal dominant manner and significantly increase the risk of developing cancer. Familial adenomatous polyposis and Lynch syndrome (hereditary nonpolyposis colorectal cancer) are the most common familial cancers with genetic defects studied, together accounting for only about 5% of colorectal cancer cases.

Among the other most well-known predisposing factors, it is worth noting inflammatory bowel diseases (ulcerative colitis, Crohn's disease) - the risk of cancer increases with the duration of these diseases. The overall incidence of colorectal cancer begins to increase approximately 8–10 years after the onset of inflammatory bowel disease and increases to 15–20% after 30 years. The main risk factors are the duration of the disease, the extent of the lesion, young age and the presence of complications.

Age is a significant risk factor: colorectal cancer is rare before age 40, but the incidence of colorectal cancer increases in each subsequent decade and peaks at 60–75 years.

There are factors that increase your risk of developing colorectal cancer. It has been established that populations of people in which the incidence of colorectal cancer is high consume foods that are low in fiber, but high in animal protein, fat and refined carbohydrates. Obesity increases the risk of developing colorectal cancer by approximately 1.5 times, and to a greater extent in men. Excessive alcohol consumption and smoking are also among the factors that increase the sporadic incidence of colon polyposis and colorectal cancer, and significantly increase the risk of cancer in patients with hereditary diseases of the large intestine (eg, colon syndrome).

What is colorectal cancer screening?

These are methods for actively identifying individuals with risk factors for developing colorectal cancer or with asymptomatic colorectal cancer, based on the use of special diagnostic methods. Screening studies for colorectal cancer help to significantly reduce the likelihood of its development, as they allow us to identify precancerous intestinal disease or cancer at an early stage and provide timely treatment.

First of all, persons who have among their first-degree relatives (children, parents, brothers and sisters) cases of colon or rectal cancer, adenomas and inflammatory bowel diseases are subject to screening. Having a relative with such a diagnosis increases the risk by approximately 2 times compared to the population as a whole.

Recommendations from a number of scientific societies for the study of colorectal cancer (American College of Gastroenterology, Multisociety Task Force on Colorectal Cancer from the American Cancer Society, American College of Radiology) contain guidelines for the timing of the first colonoscopy in the following patients:

early, before 40 years of age, in patients who have close relatives with intestinal adenoma diagnosed before the age of 60 years;

10-15 years earlier than the “youngest” colorectal cancer in the family was identified, and/or this diagnosis was made at 60 years of age or younger.

The timing of screening studies may be changed if the patient has additional risk factors for colorectal cancer: radiation exposure to the abdominal cavity at an early age for cancer, a diagnosis of acromegaly (which may lead to the development of adenomatosis of the colon), a previous kidney transplant (as a reason for long-term immunosuppressive therapy).

Symptoms of colorectal cancer

Tumors of the colon and rectum grow slowly, and a fairly long period of time may pass before the first signs may appear. Symptoms depend on the location of the tumor, type, extent of spread, and complications. The peculiarity of colorectal cancer is that it “makes itself known” quite late. In other words, such a tumor is invisible and imperceptible to the patient; only when it grows to a significant size and grows into neighboring organs and/or metastasizes does the patient begin to feel discomfort, pain, and notice blood and mucus in the stool.

The right section of the colon has a large diameter, a thin wall and its contents are liquid, so blockage of the intestinal lumen (obturation) develops last. More often, patients are concerned about gastrointestinal discomfort caused by disorders of the functions of neighboring organs - the stomach, gallbladder, liver, pancreas. Bleeding from the tumor is usually insidious, and fatigue and morning weakness caused by anemia may be the only complaints. Tumors sometimes become large enough that they can be felt through the abdominal wall before other signs appear.

The left part of the colon has a smaller lumen, the stool in it is of a semi-solid consistency, and the tumor tends to narrow the intestinal lumen in a circle, causing intestinal obstruction. Stagnation of intestinal contents activates the processes of putrefaction and fermentation, which is accompanied by bloating and rumbling in the stomach. Constipation gives way to copious loose, foul-smelling stools. The patient is bothered by colicky abdominal pain. The stool may be mixed with blood: bleeding in colon cancer is most often associated with the disintegration or ulceration of the tumor. Some patients experience symptoms of intestinal perforation with the development of peritonitis.

For rectal cancer, the main symptom is bleeding during bowel movements. Whenever bleeding or discharge from the anus is observed, even in the presence of significant hemorrhoids or diverticular disease, concomitant cancer must be excluded. There may be a urge to defecate and a feeling of incomplete bowel movement. Pain occurs when the tissues surrounding the rectum are involved.

In some cases, even before the appearance of intestinal symptoms, patients may show signs of metastatic damage - tumor spread to other organs, for example, liver enlargement, ascites (fluid accumulation in the abdominal cavity), and enlarged supraclavicular lymph nodes.

Violation of the general condition of patients can be observed in the early stages and is manifested by signs of anemia without visible bleeding, general malaise, weakness, and sometimes increased body temperature. These symptoms are characteristic of many diseases, but their appearance should be a reason to immediately consult a general practitioner.

There are many “masks” for colorectal cancer, so you should consult your doctor for advice:

with increased fatigue, shortness of breath, uncharacteristic pallor for the patient, if they were not present previously;

with prolonged constipation or diarrhea;

with frequent/constant pain in the abdominal area;

if there is visible blood in the stool after defecation;

in the presence of hidden blood in a stool test.

In case of acute pain in the abdominal area, bloating or asymmetry of the abdomen, in the absence of stool and gas, you should call an ambulance or urgently seek medical help.

Screening and diagnosis of colorectal cancer

In the presence of the complaints described above, as well as in patients belonging to a high-risk group for colorectal cancer, an examination is carried out. The most informative and generally accepted method of early diagnosis is colonoscopy - an endoscopic (intraluminal) examination of the mucous membrane of the rectum, colon and part of the small intestine (for about 2 m). All pathologically altered tissues and polyps will either be completely removed during colonoscopy, or pieces will be taken from them and sent for histological examination. If the mass is wide-based or cannot be safely removed with a colonoscopy, your doctor will consider surgery.

Once cancer is diagnosed, patients should have a CT scan of the abdomen and chest to look for metastatic lesions, as well as laboratory tests to evaluate the severity of anemia.

In 70% of patients with colorectal cancer, there is an increase in serum levels of carcinoembryonic antigen (CEA) and tumor marker CA19.9. In the future, monitoring of CEA and CA19.9 may be useful for early diagnosis of tumor recurrence. According to indications, other markers of colorectal cancer are also studied.

The main screening test for patients over 50 years of age with an average risk is colonoscopy. If there are polyps or other pathology in the colon and rectum, the frequency of examinations may increase to annual or every 3-10 years. Assessing the degree of risk of developing colorectal cancer in patients with intestinal diseases, the doctor decides on the frequency of testing individually for each patient.

Only such an active position of doctors regarding the early diagnosis of polyps and the prevention of tumors of the colon and rectum led to a slowdown in the growth rate of colorectal cancer incidence in the United States.

Treatment of colorectal cancer

Surgery for colorectal cancer can be performed in 70-95% of patients without evidence of metastatic disease. Surgical treatment consists of removing the segment of intestine with the tumor with the local lymphatic system, followed by connecting the ends of the intestine (creating an anastomosis) to preserve the natural ability to empty the intestines. In case of rectal cancer, the volume depends on the distance from the anus the tumor is located. If it is necessary to completely remove the rectum, a permanent colostomy (a surgically created opening in the anterior abdominal wall to remove the colon) is formed, through which the contents of the intestine will be emptied into a colostomy bag. Taking into account modern advances in medicine and devices for colostomy care, the negative consequences of this operation are minimized.

In the presence of liver metastases in non-depleted patients, removal of a limited number of metastases is recommended as a further method of surgical treatment. This operation is performed if the primary tumor has been completely removed, the liver metastasis is in one lobe of the liver, and there are no extrahepatic metastases. Survival after surgery for 5 years is 6-25%.

IMPORTANT!!!

The effectiveness of treatment for colorectal cancer depends on the stage of the disease at which the patient consults a doctor. Only early diagnosis of colorectal cancer makes it possible to make maximum use of the entire range of modern treatment methods and achieve satisfactory results.

Paying attention to your body and timely seeking qualified medical help increases your chances of continuing an active life even with such a serious cancer.

According to epidemiological studies, in recent decades the world has seen a catastrophic increase in the incidence of colorectal cancer (CRC): up to 1 million such patients are registered annually, of which up to 500 thousand people die within a year. Today, in most countries of Europe, Asia and the United States, colorectal cancer ranks first among malignant tumors of the gastrointestinal tract, being the second most common malignant tumor in men (after bronchopulmonary cancer) and the third in women (after bronchopulmonary cancer and breast cancer) . In the structure of mortality, colorectal cancer ranks second among malignant tumors of all localizations.

An oncology patient, according to practice, comes to oncologist-coloproctologists already with advanced stages of the disease, as a result of which up to 50% of such patients die in the first year of diagnosis of the disease. The first specialist to whom a patient with a precancerous disease or tumor of the gastrointestinal tract turns is a therapist or gastroenterologist, then an endoscopist and only then an oncologist; for rectal and colon cancer - a surgeon or coloproctologist, endoscopist and oncologist, respectively.

The majority (over 60%) of patients with colorectal cancer are admitted to oncological, surgical and coloproctological hospitals, often against the background of severe complications such as intestinal obstruction, paracancerous infiltrates, abscesses, bleeding, perforation of the colon wall. This not only significantly worsens the immediate and long-term results of surgical treatment, but also causes an increase in the proportion of patients with stomas. Even in specialized hospitals, every 3-4th operation on the large intestine ends with the formation of a stoma; 12-20% of patients are inoperable.

Due to late diagnosis of the disease, the mortality rate of patients with colon cancer within a year is 41.8%, of the rectum - 32.9%. Unfortunately, the disease in the majority of cases is detected at stages III-IV, which does not allow for gentle radical interventions, in particular, transanal microsurgical resections. The 5-year survival rate is 83% when the tumor is localized within the intestinal wall, 64% when the tumor spreads throughout the entire thickness of the intestinal wall. In the presence of metastases in the lymph nodes, this figure averages 38%, and in the presence of distant metastases (most often in the liver) - does not exceed 3%.

An important reserve for reducing the incidence and prevalence of cancer of the gastrointestinal tract, its timely diagnosis and treatment in the early stages is the formation by doctors of risk groups for tumor development (patients with precancerous diseases, unfavorable in terms of oncology, a burdened family history, etc.) and active surveillance for such patients.

Precancerous diseases of the colon include:

Polyps: diffuse familial polyposis, adenomatous polyps;
- nonspecific ulcerative colitis;
- Crohn's disease;
- diverticulosis;
- other benign and inflammatory diseases of the rectum.

Precancerous diseases are a kind of watershed between therapy, gastroenterology and oncology. Considering that the progression and growth of a tumor through the stage of dysplasia - cancer in situ - to the stage of metastasis occurs within a year, this therapeutic and diagnostic window should be actively used by general practitioners for primary and secondary prevention of cancer of this localization. In this regard, it becomes relevant to timely examination of the colon in practically healthy people to identify asymptomatic diseases (polyps, early colon cancer, etc.).

The number of cases and deaths from colorectal cancer can be significantly reduced through comprehensive screening - testing of asymptomatic patients with precancerous diseases or colorectal cancer in the early stages. The most common finding during screening is adenomatous polyps, the prevalence of which, according to screening colonoscopies, is 18-36%.

Digital examination of the rectum - annually in persons over 40 years of age;
- stool examination for occult blood - annually in persons ≥ 50 years old;
- fibrocolonoscopy - every 3-5 years in people over 50 years old (in our country, taking into account the radioecological situation - every 2 years).

The risk of developing colorectal cancer depends on a number of factors:

The presence of chronic inflammatory bowel diseases, adenomatous polyps, cancer of other localizations, etc.;
- family history (presence of one or two first-degree relatives with colorectal cancer or familial diffuse intestinal polyposis);
- age over 50 years (more than 90% of patients with colorectal cancer are people in this age category; average risk).

A preventive coloproctological program should include active detection of asymptomatic polyps and colon cancer at an early stage, their adequate and timely surgical treatment. Effective monitoring of identified patients makes it possible to prevent the occurrence of tumors in the colon in 94.4% of patients, and to prevent the progression of oncological pathology in 94.7-99.5% of cases.

Age is an important risk factor for colorectal cancer in both men and women. After 50 years, the incidence of colorectal cancer increases from 8 to 160 or more cases per 100,000 population. The number of adenomatous colon polyps in individuals aged 50-75 years increases by 20-25%. Thus, people over 50 years of age, even in the absence of symptoms, constitute a moderate risk group for colorectal cancer. The second category - a group at increased risk of colorectal cancer (20%) - consists of individuals with a genetic and family predisposition, suffering from chronic inflammatory bowel diseases and diffuse familial polyposis.

The high-risk group for colorectal cancer is defined according to the Amsterdam criteria (presence of malignant tumors in two generations, presence of cancer in a first-degree relative under the age of 50 years). In this case, colorectal cancer screening is determined by the doctor before the start of screening to select the scope of studies and the frequency of their conduct.

Stratification of risk factors for colorectal cancer:

Has the patient had a history of adenomatous polyps or colorectal cancer?
Does the patient have chronic inflammatory bowel diseases (ulcerative colitis, Crohn's disease, etc.) that predispose to the development of colorectal cancer?
Do you have a family history of colorectal cancer or adenomatous polyp of the colon? If so, how often among first-degree relatives and at what age were cancer or polyps first diagnosed?

A positive answer to any of these questions should be considered a risk factor for colorectal cancer.

Screening for colorectal cancer is a comprehensive examination and includes a test for occult blood in the stool, sigmoidoscopy, colonoscopy, X-ray contrast studies, determination of damaged DNA in stool, etc. The condition for the success of the screening program is the observance of many conditions, the most important of which are the awareness and activity of primary care physicians link, the patient’s readiness to conduct screening tests, the timeliness of their implementation and the necessary treatment, subsequent active monitoring of patients, etc.

The reason for the late diagnosis of cancer of this localization and hospitalization of patients is the lack of a state program for the prevention and early diagnosis of chronic diseases of the colon (colon polyps, colorectal cancer, ulcerative colitis, Crohn's disease, etc.), as well as a decrease in accessibility to the population, especially for residents of rural areas, specialized types of medical care, including proctology and oncology.

Broad information content among surgeons, therapists, gastroenterologists, and coloproctologists about modern requirements for colorectal cancer screening contributes to timely diagnosis and treatment of this pathology at the initial stage and a reduction in the incidence of colorectal cancer in the population.

Thus, combining the efforts of the main links in the field of health care and the approval of targeted government programs will help solve the problem of successful prevention and treatment of colon cancer, which remains relevant and requires immediate action.

Screening for colorectal cancer includes:

Fecal occult blood test

Already in the early preclinical stages of colorectal cancer development, blood and other elements of colon tissue can be detected in the intestinal contents, which can be determined by examining stool for occult blood. As evidenced by the results of randomized trials, the use of this study as a screening study can improve the diagnosis of the disease in the early stages, reduce mortality rates by 15-45%, depending on the type of study performed and the frequency of its conduct.

Currently, one of the most effective methods for diagnosing cancer and precancerous conditions is a rapid immunochromatographic rapid test (ICA test). Its advantages include the absence of the need to prepare the patient for the study or adherence to a certain diet, detection of only intact human hemoglobin, which eliminates the possibility of false-positive reactions, high sensitivity (more than 95%) and specificity. The ICA method - CITO TEST FOB - is fast, easy to use, highly sensitive, does not require special equipment and reagents, trained medical personnel and significant material costs (cost equivalent to 4-5 US dollars).

Determination of damaged DNA in stool

Colorectal carcinogenesis is accompanied by a number of acquired genetic mutations that can cause changes in the normal mucous membrane of the colon up to incurable stages of cancer. Today it is possible to obtain human DNA from stool and test it for genetic and other damage. Studies have confirmed the sensitivity of this method at 91% for cancer and 82% for colon adenomas with a specificity of 93%. Rapid development of this screening method can be expected in the future.

Sigmoscopic examination

The use of sigmoscopic examination makes it possible to reduce mortality from colorectal cancer localized within the reach of the sigmoidoscope by two thirds. Using flexible sigmoidoscopy, you can visually examine the inner surface of the colon at a distance of up to 60 cm from the anus. This technique not only detects colorectal polyps and cancer, but is also used to remove polyps and take biopsies for pathological examination. The advantages of flexible sigmoidoscopy include the ability to be performed by a non-endoscopist; the procedure requires less time than a colonoscopy; colon preparation is easier and faster; there is no need for sedation. Case-control studies have shown that screening sigmoidoscopy reduces mortality from colorectal cancer by 60-70%. Life-threatening complications occur in 1 case per 10,000 examinations.

Colonoscopy examination

This is one of the most informative methods for examining the colon, allowing not only to identify polyps, take a biopsy from any part of the colon or in the area of the detected tumor, but also to perform surgery - polypectomy in any part of the colon. There is evidence that screening colonoscopy can significantly reduce the incidence of colorectal cancer, especially in patients with adenomatous polyps, and reduce the mortality of patients with colorectal cancer. However, the complexity of implementation, high cost and inconvenience for the patient significantly limit the use of colonoscopy as a screening test. A 5-year interval between screening tests for individuals at average risk of developing colorectal cancer (if the previous test was negative) is justified, since the average time for an adenomatous polyp to develop into cancer is at least 7-10 years. However, in our country, taking into account the radioecological situation, this period should be reduced to 2-3 years. In detecting dysplasia of the mucous membrane and tumors of the colon, chromoendoscopic examination using methylene blue or indigo carmine provides significant assistance.

Virtual colonoscopy examination

Spiral computed tomography followed by computer processing provides a high-resolution three-dimensional image of the colon. The study is non-invasive and is not accompanied by the development of serious complications. It is performed after standard preparation of the colon and air insufflation into it, which is inconvenient for the patient and is accompanied by radiation exposure. Because this method cannot visualize flat adenomas, its economic feasibility (procedural cost equivalent to US$80–100) is not sufficient to qualify it as a widely used screening test.

Irrigoscopic (irrigographic) examination

Currently, there are no randomized studies demonstrating a reduction in colorectal cancer mortality or morbidity as a result of irrigatory screening in individuals at average risk of developing the disease.