Most colorectal cancers are due to old age and lifestyle factors, with only a small number of cases due to underlying genetic disorders. Other risk factors include diet, obesity, smoking and lack of physical activity. Dietary factors that increase risk include red meat, processed meat, and alcohol. Another risk factor is inflammatory bowel disease, which includes Crohn's disease and ulcerative colitis. Some of the inherited genetic disorders that cause colorectal cancer include familial adenomatous polyposis and polyposis without hereditary colon cancer; However, these represent less than 5% of cases. It is usually a benign tumor, often in the form of a polyp, which over time becomes cancerous.
Bowel cancer can be diagnosed by a sigmoidoscopy or colonoscopy. This is followed by medical imaging to determine if the disease has spread. Screening is effective in preventing and requiring death from colorectal cancer. Screening, by one of several methods, is recommended for 50 to 75 years of age. During colonoscopy, small polyps can be removed if found. If a large polyp or tumor is found, a biopsy can be checked if it is cancerous. Low risk of aspirin and other non-anti-inflammatory drugs. Their general use is not recommended for this purpose, however, due to side effects.