Causes and risk factors of colon cancer
Causes and risk factors of colon cancer, Complex events: More rarely hereditary
The development of colorectal cancer is a complex process in which several factors are involved. In seven out of ten cases, sporadic tumors are present, with a quarter of the patients having a familial burden, ie family colorectal cancer, without a clear cause of heredity, and only 5% is a genetic one (Hereditary) form of colorectal cancer, such as familial adenomatous polyposis (FAP) or hereditary non-polypoid colorectal carcinoma (HNPCC, Lynch syndrome). The average risk of developing colorectal cancer in life is in the German population with no familial or genetic burden at around six percent. If first-degree relatives are affected by colorectal cancer or a benign adenoma of the colon, this risk is significantly higher. In humans with certain genetic changes, eg in family adenomatous polyposis, the life-time risk for colorectal cancer rises to more than 90 percent.
Sporadic tumors: adenomas as the starting point
Sporadically occurring colorectal cancer arises in most cases from mucous membrane polyps, so-called adenomas. These initially benign growths of the intestinal mucosa can develop into malignant tumors in the course of many years, and are therefore classified by the medical profession as the precursors of colorectal cancer. Molecular mechanisms as well as tumor-promoting and tumor-inhibiting genes play a role. They ensure that healthy intestinal cells are transformed into malignant cells. Detecting and removing the adenomas in a colonoscopy immediately prevents their conversion to colorectal cancer.
The development of adenomas, and thus also of colorectal cancer, is fostered by certain risk factors, most of which are lifestyle-related:
- Nutrition: Regular consumption of large quantities of red meat (eg pork, beef) or processed meat (eg sausage, chilled meat), low-fiber diet with little fruit and vegetables
- Little physical movement
- Overweight and obesity (obesity) with a high percentage of abdominal fat
- High alcohol consumption
- Higher age: The incidence of colorectal cancer increases with the age of life, which is why this is regarded as an independent risk factor by physicians
- Diabetes mellitus type 2
- Chronic inflammatory diseases such as ulcerative colitis
- Gallbladder removal (cholecystectomy)
- Radiotherapy in the pelvis
Hereditary colorectal cancer
People with so-called familial adenomatous polyposis (FAP) are already suffering from innumerable benign mucosal polyps in the colorectal at a very young age. Practically always, colorectal cancer develops and this also in a still young age. In hereditary colorectal cancer without polyposis, the hereditary (hereditary) non-polypoid colorectal cancer (HNPCC, Lynch’s syndrome), those affected suffer an 80% chance of colorectal cancer.