Bowel cancer – is one of the most common types of cancer. It is more than 10% of all cancers. Bowel cancer is often called colorectal, as it includes both colon and rectal cancer. The incidence of colon cancer is slightly higher. The proportion of morbidity between women and men is almost the same, but women get sick a little more often. The greatest incidence is observed after the age of 60 years. More than half of the cases are diagnosed late, as patients are late to see a doctor. This is partly due to the fact that intestinal cancer does not cause any specific complaints until it reaches a large size.
How is bowel cancer diagnosed?
Colon cancer, depending on the type of affected cells, can be divided into three main types:
- Adenocarcinoma is a large part of the cases of colon cancer
- Scarrozza tumor, when during the growth of the tumor hard a special protein – collagen, which makes the intestinal wall of a rigid, inelastic; therefore, a “solid” tumor;
- Neuroendocrine cancer, which can be formed in hormone-producing cells.
In most cases, colorectal cancer begins with abnormal cell growth or & dysplasia. Dysplasia is aprecancerous condition that may or may not later become cancer. In the case of colorectal cancer, the precancerous condition is often associated with polyps (the growth of the intestinal mucosa; often on the “leg”) in the mucosa of the colon or rectum. Polyps of the colon and rectum are most often benign, usually do not cause symptoms. However, they can be the cause of painless rectal bleeding or invisible bleeding (therefore it is called hidden bleeding). Polyps can be either single or multiple. The incidence of polyps increases with age. Due to the increased reproduction of cells in the polyp, under the influence of various adverse (carcinogenic)factors, the mechanism that regulates the reproduction of cells can “deteriorate”, cells change and begin to divide intensively, i.e. multiply. The epithelium loses its characteristic form, the formation of new cells becomes faster and eventually lost control of cell division – occurs malignization. Malignant (cancer) cells are able to multiply indefinitely and spread throughout the body. The whole process of malignancy can last 10 to 20 years or more.Initially, cancer develops in the mucosa and does not grow into deeper layers. Next, cancer cells can germinate the entire wall of the intestine and penetrate the surrounding tissue.
The overall risk of cancer, if the polyp is not operated on, is: 2.5% for 5 years, 8% for 10 years and 24% for 20 years after the diagnosis of the polyp.
Within 5 years, the diameter of the polyp can reach 1 cm in Another 5-10 years the cells of the polyp can become cancerous. Usually it takes another 5-10 years before symptoms appear, but at this time the cancer can already reach a late stage.
The incidence of colon cancer is significantly higher among patients with inflammatory bowel diseases (ulcerative colitis and Crohn’s disease). It is associated with the duration and volume of the disease, as well as with the degree of changes caused by the disease. If the colon is a long inflammatory process caused by ulcerative colitis or Crohn’s disease, in the cells lining the intestine, irreversible changes may occur. The greatest risk is observed among patients in whom the disease lasts more than 10 years and those who have an inflammatory process affected the entire colon or most of it (total or total colitis).
Symptoms of bowel cancer depend on the location and stage of the tumor. However, similar symptoms can be observed in other diseases. Important is the fact that often symptoms appear only in the later stages of cancer.
The most common symptoms are:
- blood in the stool,
- a lot of fecal mucus,
- diarrhea or constipation;
- abdominal pain,
- weight reduction,
- weakness, impotence.
However, none of these symptoms is specific only for colorectal cancer. For example, blood in the stool may appear in hemorrhoids, and diarrhea can cause intestinal infection.If the bleeding caused the tumor, it can last for many months. In this case, a person may not even notice that he is losing blood, and his main complaints are shortness of breath, fatigue and dizziness, which are essentially symptoms of anemia. When the tumor reaches a large size, it can completely clog the intestine. In this case, blockage or significant narrowing of the intestine prevents the movement of feces and intestinal gases, so there is bloating. The contents of the intestine can not penetrate the blockade, accumulates in the intestine, there is the absorption of not only water and nutrients, but also toxins that cause nausea and vomiting. In this case, emergency medical care is necessary, since an increase in pressure in the intestine can cause its rupture, as a result, all the contents of the intestine will fall into the abdominal cavity, causing a life-threatening acute surgical pathology, called peritonitis.
Patients with suspected bowel cancer need an urgent examination. When manual examination in the rectum, you can find a pathological mass, which may indicate cancer of the rectum, located close to the anus. However, in order to explore the segments of the intestinal tract, rectum or confirm the presence of tumor mass in the rectum needed visualize diagnostic tests.
Endoscopy, which in the study of the intestine is called colonoscopy, is the main method of investigation for diagnosing intestinal cancer. This is an outpatient procedure, during which the rectum and colon are examined from the inside using a special probe (endoscope). An endoscope is a long, flexible beam of quartz optical fibers about the thickness of a finger. This instrument is placed in the rectum. The colon expands with a small amount of air so that the doctor can examine the tissues lining it (the image can be seen on the monitor). If an intestine it is necessary to assess in more detail through the endoscope instrument is administered for painless biopsies or obtaining the tissue sample. These tissues are sent to the lab for analysis. Microscopic analysis of tissue biopsy is essential for the correct diagnosis and determination of the stage of intestinal cancer.
During colonoscopy, you can examine the entire colon, and another method of examination – sigmoscopy allows you to inspect the lower third of the colon, rectum and Sigma. For this there are two types of tools – the proctoscope and flexible sigmoscopy. The rectoscope is used for patients who are not prepared for examination, i.e. the lower part of the intestine is not cleaned with laxatives or enemas. However, with the help of a rectoscope, you can inspect about 20 cm of the rectum, in turn, a flexible sigmoscope is more difficult to use, but allows you to get an image of most of the descending colon and rectum. If imaging diagnostic studies indicate that a more detailed examination is needed, a complete colonoscopy with biopsy should be performed.
It is very important to distinguish intestinal cancer from Crohn’s disease and severe ulcerative colitis (it should be noted that both diseases are risk factors for intestinal cancer). In the case of severe ulcerative colitis, endoscopic signs can be observed – General inflammation of the mucous membrane, swelling, fragility of the mucosa with hemorrhages. In Crohn’s disease repeated cycles of ulceration, which are followed by periods of healing, sometimes cause uplift of a section of the mucosa, which is similar to polyps, which are called fake or pseudopolyposis. A characteristic feature of Crohn’s disease in endoscopic examination-a typical type of mucosa , like a cobblestone pavement.
Barium enema (or air contrast barium enema) – a method of X-ray examination, which is used to obtain images of the colon. Two days before the study with barium enema, the patient should take a light, mostly liquid food, and in the evening before the examination it is necessary to take a laxative. On the day of the examination, an enema with barium is introduced, air is allowed into the colon and an x-ray of the abdomen is taken.