What causes colorectal cancer, and who is at risk of developing it?
The exact cause of most colorectal cancers is not yet known. About 75% of colorectal cancers occur in people with no known risk factors. Some conditions that may increase a person’s risk of developing colorectal cancer include having— • A personal or family history of colorectal polyps or colorectal cancer. • Inflammatory bowel disease (ulcerative colitis or Crohn’s disease). • A genetic syndrome such as familial adenomatous polyposis (FAP) or hereditary non-polyposis colorectal cancer (Lynch syndrome).
