What causes bowel cancer?

Bowel cancer develops when cells in the colon or rectum acquire growth changes, sometimes through polyps or inherited syndromes. A bowel polyp is a growth in the bowel lining; some types can gradually become cancerous, while many do not. The presence of a polyp does not by itself mean cancer is present.

As cells divide, changes in their control systems can allow abnormal growth and invasion into nearby tissue. Some cancers develop from a polyp over time; others arise without a known precursor. Familial adenomatous polyposis can cause many bowel polyps and requires specialist surveillance. Lynch syndrome affects the way cells repair certain types of DNA damage and can raise bowel-cancer risk. Family history, age, inflammatory bowel disease, smoking, alcohol, excess body weight, and low physical activity may also influence risk, but a person can develop bowel cancer without any single identifiable cause.

Follow bowel-screening invitations and discuss earlier assessment if a close relative has bowel cancer or a known inherited syndrome. Report persistent changes in bowel habits, rectal bleeding, unexplained weight loss, abdominal pain, or unusual tiredness. If a polyp is found, ask what type it is and when follow-up is needed. Do not assume that removing one polyp removes every future risk; surveillance depends on the findings and your personal history.

Arrange timely medical review for blood in the stool, black stools, a persistent bowel-habit change, ongoing abdominal discomfort, unexplained weight loss, or tiredness that may reflect anaemia. Seek urgent care for heavy bleeding, faintness, severe abdominal pain, repeated vomiting, or a swollen abdomen with inability to pass stool or gas. These symptoms have several possible causes, but they should not be ignored.

Could my family history suggest an inherited bowel condition? Am I due for screening or surveillance? What did my polyp or biopsy result show? Which symptoms should prompt urgent care? Would a genetics referral help my family?