Colon and rectal cancer - causes, signs, diagnosis

In most countries of the world colon and rectal cancer (colorectal cancer) occupies one of the leading places in the overall structure of oncological diseases in terms of morbidity, disability and mortality, and ranks 1st in terms of growth rates. The increase in registered morbidity is accompanied by an increase in the frequency of its neglect - stages III-IV of the disease are diagnosed in almost half of newly diagnosed patients. That is why the problem of diagnosing and treating colorectal cancer is extremely relevant and is an important section of not only a medical problem.

Colorectal cancer is a group of malignant neoplasms of the colon, sigmoid and rectum. There are no specific, characteristic symptoms of the disease that allow timely diagnosis of the disease. Most often they are discovered during preventive examinations or in surgical hospitals, where they are urgently hospitalized with a clinical picture of acute intestinal obstruction or intestinal bleeding. The disease manifests itself with minor discomfort for a long time or is asymptomatic.

However, there are a number of symptoms that, in some cases, allow timely diagnosis of pathology. The presence of certain symptoms depends on the location of the tumor. Thus, when the right half of the colon is affected (blind, ascending, proximal part of the transverse colon), general clinical manifestations prevail - weakness, anemia, bleeding, diarrhea, pain, etc. When the left half is affected, the leading ones are constipation and bloating, cramping pain, irregular bowel movements (constipation is replaced by diarrhea), development of a picture of intestinal obstruction. In case of rectal cancer, the leading symptoms are frequent false urge to stool with discharge of mucus, pus and blood during bowel movements, gas and fecal incontinence, persistent constipation and acute pain, etc.

Risk factors for the development of colon and rectal cancer include chronic, inflammatory and other intestinal diseases (ulcerative colitis, Crohn's disease, intestinal polyps and adenomas), genetic predisposition, poor nutrition (insufficient consumption of vegetables and fruits), age over 50 years, immunodeficiency states , etc.

According to histological structure, adenocarcinoma develops most often (about 75%) in the intestine. Less common are signet ring cell, squamous cell, and undifferentiated tumors.

When determining the stage of the disease, the Russian classification of cancer is used, including 4 stages of tumor growth, based on taking into account the degree of local spread (the degree of tumor infiltration, its interaction or germination into surrounding organs and tissues), as well as extraorgan growth (the absence or presence of lymphogenous and distant organ metastases ). The International TNM classification is also widely used.

Colorectal cancer is characterized by various complications that affect both the course of the disease and leading to the death of the patient, as well as its prognosis. The most common symptoms are intestinal obstruction, bleeding, and general complications. Terrible irreversible consequences affecting the prognosis of the disease and treatment results are observed with the development of metastases to distant organs - the liver, lungs, brain, and other organs.

A number of highly informative methods are used to diagnose intestinal tumors. The simplest is a blood culture test (stool occult blood test) - an examination of stool for the presence of blood that is not visible to the naked eye. When blood is detected, clarifying diagnostic methods are indicated. In most cases, rectal cancer is detected by digital examination of the rectum. When the tumor is localized in the overlying parts of the intestine, endoscopic examinations are highly informative - rectoscopy, sigmoidoscopy, colonoscopy - examination of the intestinal mucosa, which allows, if the presence of pathology in the organ is suspected, to perform a tumor biopsy followed by histological examination. Radiological methods for examining the intestines with contrast are widely used in clinical practice - irrigoscopy and irrigography, examination of the gastrointestinal tract with oral administration of a contrast agent.

To study the extraorgan prevalence of the tumor process, ultrasound examination of the rectum, abdominal organs and lymphatic system, chest radiography, computed tomography (CT), positron emission computed tomography (PET-CT), magnetic resonance imaging (MRI), scintigraphy are used. (radionuclide studies of the lymphatic system, bone skeleton, various parenchymal organs), other methods. Clarifying diagnosis of the stage of the disease is very important for choosing an adequate treatment method.

The main treatment method for colorectal cancer currently is surgery. The main emphasis is on performing organ-preserving (organ-preserving) operations. However, their implementation is possible only in the initial stages of the disease, in the absence of distant metastases. Resection of an organ is performed - tumor is removed en bloc with regional lymph nodes. In this case, when the tumor grows into surrounding organs or tissues, it is removed en bloc within healthy tissues. In IIb, III and IV patients, combined and complex treatment methods are used in the treatment of patients - the use of radiation or chemotherapy in the preoperative and/or postoperative periods, or their combination - chemo-radiation therapy.

Given the high chemo- and radioresistance of colorectal cancer to drugs and ionizing radiation, various approaches have been actively developed in recent decades to enhance their damaging effect on tumor cells - the so-called radiomodifiers. These include artificial hyperglycemia, hypoxic radiotherapy, photosensitization, synchronization of the cell cycle of tumors, etc. Also worthy of attention is targeted therapy (drugs that slow down the growth and progression of the tumor process) and, especially very successfully used in recent years and proven to be a highly effective innovative method, the cytokinogenetic method therapy, allowing success to be achieved even in cases where all other treatment options have been exhausted.

The prognosis of the disease depends (not only for colorectal cancer), mainly on the stage of the disease. The earlier a tumor is diagnosed and treated, the higher the patient’s chances of a complete cure. Thus, with stage I of the disease, recovery is observed in 95-98% of cases. That is why in the problem of anti-cancer control the main emphasis is on the early diagnosis of cancer.