Colon cancer is a malignant tumor of epithelial origin, localized in the colon. Initially, it is asymptomatic, subsequently manifested by pain, constipation, intestinal discomfort, impurities of mucus and blood in the fecal masses, deterioration and signs of cancer intoxication. Often a node in the projection of the organ is palpated. With progression, intestinal obstruction, bleeding, perforation, infection of neoplasia and the formation of metastases are possible. The diagnosis is made taking into account the symptoms, radiography, CT, MRI, colonoscopy and other studies. Treatment – surgical resection of the affected part of the intestine.
ICD 10
C18 C19
Meaning
Colon cancer is a malignant neoplasm originating from the cells of the mucous membrane of the large intestine. It ranks third in prevalence among oncological lesions of the digestive tract after tumors of the stomach and esophagus. According to various data, it is from 4-6 to 13-15% of the total number of malignant tumors of the gastrointestinal tract. It is usually diagnosed at the age of 50-75 years, it is equally often detected in male and female patients.
Colon cancer is widespread in developed countries. The leading positions in the number of cases of the disease are occupied by the USA and Canada. Quite high incidence rates are observed in European countries. The disease is rarely detected in residents of Asian and African states. Colon cancer is characterized by prolonged local growth, relatively late lymphogenic and distant metastasis. The treatment is carried out by specialists in the field of clinical oncology, proctology and abdominal surgery.
Causes
Experts believe that colon cancer is a polyethological disease. An important role in the development of malignant neoplasia of this localization is played by the peculiarities of the diet, in particular – an excess of animal fats, a lack of coarse fiber and vitamins. The presence of a large amount of animal fats in food stimulates the production of bile, under the influence of which the microflora of the large intestine changes. In the process of splitting animal fats, carcinogenic substances are formed that provoke colon cancer.
Insufficient amount of coarse fiber leads to a slowdown in intestinal motility. As a result, the formed carcinogens are in contact with the intestinal wall for a long time, stimulating the malignant degeneration of mucosal cells. In addition, animal fat causes the formation of peroxidases, which also have a negative effect on the intestinal mucosa. The lack of vitamins, which are natural inhibitors of carcinogenesis, as well as fecal stagnation and constant injury by fecal mucosa in areas of natural bowel bends exacerbate these adverse effects.
Recent studies indicate that a certain role in the occurrence of colon cancer is played by sex hormones, in particular progesterone, under the influence of which the intensity of the release of bile acids into the intestinal lumen decreases. It has been established that the risk of developing malignant neoplasia of this localization in women with three or more children is twice as low as in unborn patients.
There are a number of diseases that can transform into colon cancer. These diseases include:
- Crohn’s disease
- nonspecific ulcerative colitis
- polyposes of various genesis
- single adenomatous polyps
- diverticulosis.
The probability of these pathologies degenerating into colon cancer varies greatly. With familial hereditary polyposis without treatment, malignancy occurs in all patients, with adenomatous polyps – in half of the patients. Intestinal diverticula are extremely rare.
Classification
Taking into account the type of growth, exophytic, endophytic and mixed forms of colon cancer are distinguished. Exophytic cancer can be nodular, villous-papillary and polypoid, endophytic – circularly-stricturing, ulcerative-infiltrative and infiltrating. The ratio of endophytic and exophytic neoplasias is 1:1. Exophytic forms of colon cancer are more often detected in the right parts of the intestine, endophytic – in the left. Taking into account the histological structure, adenocarcinoma, cricoid-cell, solid and scyrrhous colon cancer are distinguished, taking into account the level of differentiation – highly differentiated, medium-differentiated and low-differentiated neoplasms.
According to the traditional four-stage classification, the following stages of colon cancer are distinguished.
- Stage I – a node with a diameter of less than 1.5 cm is detected, not extending beyond the submucosal layer. Secondary foci are absent.
- Stage IIa – a tumor with a dimeter over 1.5 cm is detected, spreading no more than half the circumference of the organ and not extending beyond the outer wall of the intestine. There are no secondary foci
- Stage IIb – colon cancer of the same or smaller diameter is detected in combination with single lymphogenic metastases.
- Stage IIIa – neoplasia extends to more than half of the circumference of the organ, and extends beyond the outer wall of the intestine. There are no secondary foci.
- Stage IIIb – colon cancer of any diameter and multiple lymphogenic metastases are detected.
- Stage IV – a neoplasm with invasion into nearby tissues and lymphogenic metastases or neoplasia of any diameter with distant metastases is determined.
Colon cancer symptoms
Initially, colon cancer is asymptomatic. Subsequently, pain, intestinal discomfort, stool disorders, mucus and blood in the fecal masses are observed. Pain syndrome occurs more often when the right parts of the intestine are affected. At first, the pain is usually non-intense, aching or dull. With progression, sharp cramping pains may appear, indicating the occurrence of intestinal obstruction. This complication is more often diagnosed in patients with lesions of the left intestine, which is due to the peculiarities of neoplasia growth with the formation of a circular narrowing that prevents the advancement of intestinal contents.
Many patients with colon cancer complain of belching, appetite disorders and abdominal discomfort. These signs are more often found in transverse cancer, less often in lesions of the descending and sigmoid colon. Constipation, diarrhea, rumbling and flatulence are typical for left-sided colon cancer, which is associated with an increase in the density of fecal masses in the left intestine, as well as with frequent circular growth of neoplasms in this area.
Neoplasia of the sigmoid colon is characterized by impurities of mucus and blood in the feces. With other localizations of colon cancer, this symptom is less common, because when moving through the intestine, the secretions have time to be partially processed and evenly distributed through the fecal masses. Palpation colon cancer is more often detected when located in the right parts of the intestine. It is possible to probe the node in a third of patients. The listed signs of colon cancer are combined with the general signs of cancer. Weakness, malaise, weight loss, pallor of the skin, hyperthermia and anemia are noted.
Complications
Along with the intestinal obstruction already mentioned above, colon cancer can be complicated by perforation of the organ due to germination of the intestinal wall and necrosis of neoplasia. With the formation of foci of decay, there is a risk of infection, the development of purulent complications and sepsis. With germination or purulent melting of the vessel wall, bleeding is possible. When distant metastases occur, there is a violation of the activity of the relevant organs.
Diagnostics
Colon cancer is diagnosed using clinical, laboratory, endoscopic and radiological data. First, complaints are clarified, the anamnesis of the disease is clarified, a physical examination is performed, including palpation and percussion of the abdomen, and a rectal examination is performed. Then, patients with suspected colon cancer are prescribed laboratory and instrumental diagnostics:
- X-ray examination. Irrigoscopy reveals filling defects. If intestinal obstruction or perforation of the colon is suspected, an overview radiography of the abdominal cavity is used.
- Colonic endoscopy. Patients undergo a colonoscopy to assess the localization, type, stage and type of colon cancer growth. During the procedure, an endoscopic biopsy is performed, the resulting material is sent for morphological examination.
- Laboratory tests. A stool test for hidden blood, a blood test to determine the level of anemia and a test for cancer-embryonic antigen are prescribed.
- Additional methods. CT and abdominal ultrasound are performed to detect foci in lymph nodes and distant organs.
Colon cancer treatment
The treatment is operative. Depending on the prevalence of the process, radical or palliative surgery is performed:
- Organ-preserving operations. With colon cancer, there are one-stage, two- or three-stage. During the simultaneous intervention, hemicolectomy is performed – resection of the colon area with the creation of an anastomosis between the remaining parts of the intestine. With multi-stage operations for colon cancer, colostomy is performed first, then the affected part of the intestine is removed (sometimes these two stages are performed simultaneously), and after a while the continuity of the intestine is restored by creating a direct anastomosis.
- Radical extended operations. With advanced colon cancer, extended interventions are performed, the volume of which is determined taking into account the lesion of lymph nodes and nearby organs.
- Palliative care. If radical removal of neoplasia is impossible, palliative operations are performed (colostomy, bypass anastomosis formation). In colon cancer with the development of perforation, bleeding or intestinal obstruction, a stoma or bypass anastomosis is also applied, and after the patient’s condition improves, a radical operation is performed. In colon cancer with distant metastases, chemotherapy drugs are prescribed.
Prognosis and prevention
The prognosis for colon cancer is determined by the stage of the oncological process. The average five–year survival rate at the first stage is from 90 to 100%, at the second – 70%, at the third – 30%. All patients who have undergone surgery for neoplasms of this localization should be under the supervision of an oncologist, regularly undergo radiological and endoscopic examinations to detect local relapses and distant metastases.