Over the lifetime of an average person in the UK, about six people will develop bowel cancer, and this rate seems to be increasing steadily over time. [See reference 1] Almost all cases occur over the age of about 50 years, and the risk increases rapidly with advancing age.
The bowel is a long passage, and it can be described as a beginning half (the proximal colon) and an end half (the terminal or distal colon). Screening with a flexible tube is relatively simple, but its effectiveness is largely confined to the distal part of the bowel. On the other hand, the major benefit of aspirin is in reducing growths is in the first half of the bowel, the proximal colon. [See reference 5 and 6 below]
Both screening of the bowel (colonoscopy), and low-dose aspirin are beneficial, but both have risks. Both can cause bleeding, screening from the bowel, aspirin from the stomach. Each however has also a more serious danger. Rarely, the bowel wall can be damaged and even perforated during screening ,[See reference 8 below] and rarely aspirin can lead to a haemorrhagic stroke. These events are however rare and are more than outweighed by the benefit each confers. [See sourxces 6 and 7]
Everyone should therefore accept bowel screening if it is offered, and everyone aged over about 50 should think seriously about taking a small dose of aspirin (70-100 mg daily…. but do read the section on ‘Aspirin and Bleeding’ first.