Colorectal cancer is a tumor that develops from cells lining the inner lining of the colon and rectum. It mainly affects men and women after 50 years. Through screening, cancer can be detected and treated early in the disease with a cure rate of 9 out of 10 cancers.
What is colorectal cancer?
Colorectal cancer is a cancer that develops at the expense of the glandular cells of the lining of the lining of the colon or rectum.
The colon consists of four large parts in which the water will be reabsorbed and where feces will be formed. These different parts take their name from their anatomical location. The colon draws a kind of square frame around the small intestine. Thus one speaks of “ascending colon” (or right colon) which begins at the end of the ileum by the “cecum” and which goes up to the right towards the liver. Then a first curve is drawn with the “transverse colon”, which as the name suggests, crosses the abdomen from right to left until below the stomach, at the level of the spleen. The colon sets a new angle to become the “descending colon” (or left colon) that runs down to the level of the pelvis and that describes a last small curvature where it will take the name of “sigmoid colon”, to end in the “rectum”. The colon is about 1m50 long with a diameter of about 4 cm.
The walls of the colon and rectum are lined with “glandular cells,” which under certain circumstances may sometimes undergo modifications that make them abnormal and increase their multiplication. The colon and rectum contain different types of cells that can each cause a specific form of cancer. In most cases, colorectal cancers develop from the glands, called “Lieberkühn’s glands”, which line the lining of the colon and rectum wall. This form of cancer is called “adenocarcinoma”.
Most of the time, the changes that affect the glandular cells will result in the formation of completely benign “polyps”. But sometimes, the rapid proliferation of these cells will evolve into a cancerous lesion and become a cancer proper: “adenocarcinoma”. This type of cancer accounts for more than 95% of all types of colorectal cancer. In more than 80% of cases, it comes from a benign tumor, or “adenomatous polyp”, which evolves slowly and eventually becomes cancerous.
When “adenomatous polyps” are treated early, with screening, it is much easier to monitor and intervene in time for cancer to develop and evolve.
What are the causes of colorectal cancer?
There is no identifiable cause of occurrence of colorectal cancer. However, there are risk factors that can promote cancer development. It is important to bear in mind that the presence of one or more risk factors does not systematically result in cancer. Similarly, the absence of a recognized risk factor does not prevent the development of colorectal cancer.
Proven risk factors include age, family history, presence of polyps, and two genetic diseases, “familial adenomatous polyposis” and “Lynch syndrome”. Age is often a risk factor found in most cancers. For the general population, it is considered that the risk starts from age 50 and continues until age 80. The average age of onset and discovery of colorectal cancer is approximately 70 years. Then, having people in your family who have already had colon cancer increases the risk of making one yourself. It is estimated that this risk is twice as great when it comes to a first-degree affiliate member, ie parents, children or siblings, and increases even more if the cancer is occurred before the age of 50. The presence of benign polyps in large numbers may also increase the risk of degeneration to cancer. Although most of the time, they are not serious, removing the polyps can return to a normal level of risk. Finally two genetic diseases are at very high risk of colorectal cancer before the age of 30 years. The first is “familial adenomatous polyposis” (PAF), which is a hereditary disease that causes the development of several thousand polyps in the colon. Even though these polyps are no more likely to develop into cancer than an isolated polyp, their large numbers mathematically increase the likelihood of neoplasia. The second is the “Lynch syndrome”, also called “hereditary colorectal cancer without polyposis”. This hereditary genetic disease also causes polyps, but in less quantity than PAF. In women, there is an associated risk of developing endometrial cancer.
Who are the people at risk for colorectal cancer?
Beyond the identified risk factors, certain other pathologies or lifestyle habits are likely to be associated with the occurrence of colorectal cancer.
Diabetes or inflammatory bowel diseases such as ulcerative colitis or Crohn’s disease are more often associated with colorectal cancer.
Among the habits of life, some may seem innocuous but are supported by several scientific studies. At the level of food, are pointed the excessive consumption of red meat, foods rich in animal fats, and the over-cooking of food (barbecue ..). At the level of health and diet, we are concerned with overweight or obese people, tobacco and alcohol users, and people who are not physically active.
What are the signs of colorectal cancer?
Colorectal cancer is characterized by a slow and low-noise evolution.
In the early years of development, especially in the polyp stage, no sign is visible or noticeable. This is where the value of screening campaigns lies, to intervene before the lesion worsens. But as time passes and cancer settles, the first signs appear. They may be either related to the direct consequences of cancer on the colon, or related to its extension to neighboring organs.
The most common sign is the presence of blood in the stool. This reflects the presence of intestinal mucosal pain as the cancerous lesion spreads and touches a small blood vessel. Blood can be mixed with excrement or not. Its color is usually red because the blood does not have time to be fully digested by the digestive tract, but can still be more or less dark. Sometimes the bleeding is so small that it is not possible to distinguish it with the naked eye, hence the interest of screening kits.
The second major sign is the presence of digestive disorders. They can manifest themselves in any form: chronic diarrhea, sudden constipation, cramps, gas or persistent bloating, narrower stools than usual, an urge to go to the stool or sensation to have not expelled all the faecal content.More general and non-specific signs of colorectal cancer may also appear as urinary tract infections, jaundice, intense fatigue, loss of appetite, or weight loss.