Colon cancer refers to all malignant tumors of the intestine. Colon cancer is the second most common cancer in both men and women and more than six percent of all Germans in the course of their lives comes down with this disease. Colorectal cancers rarely produce symptoms in the early stages, and almost always they are formed from benign colon polyps.
Colorectal cancers often show no symptoms for a very long time. Only when the tumor is bleeding extensively, or if it constricts the intestine significantly, it shows typical symptoms like blood or mucus in the stool. Also intestinal cramps, stools that are narrow and pencil-thin, or like goat droppings, diarrhea and constipation with often nagging flatulence can also be signs of a bowel cancer. Due to the blood loss anemia can occur and loss of efficiency, fatigue and general weakness. As a result of the disease, many patients may suffer severe weight loss with the development of a tumor cachexia (wasting syndrome).
Invisible (occult) bleeding, which can be determined with stool tests, is the only early symptom. In some countries, this test is used as a screening for colorectal cancer. 85 to 90 percent of malignant colorectal tumors are adenocarcinomas of the colon, which are derived from the glands of the intestinal mucosa. Often, central abscess (ulcer) and tissue destruction (necrosis) can be found when discovering the tumor.
The main risk factors are age and the presence of colon polyps which often degenerate. Also, a general genetic tendency cannot be ruled out: colorectal cancer in family member triples your risk obtaining colon cancer. Also patients with ulcerative colitis are at risk. Patients with Crohn’s disease carry a slightly increased risk of colorectal cancer compared to the general population.
Malnutrition is also considered a possible cause for colon cancer. This includes an excessive caloric intake, fat and meat-rich diet, and a low fiber diet.
In industrial developed countries, the number of new cases of colorectal cancer has increased significantly in the last 30 years. Colon cancer is one of the most common malignancies in Central Europe with an annual number of new cases amounting to about 20-40 per 100,000 inhabitants. The global number of new cases is estimated at one million per year. Men are affected slightly more often than women, the gender ratio is about 60:40.