History of colorectal polypectomy and risk of subsequent colorectal cancer.

In a case control study, which formed part of a large, population-based investigation of the incidence, aetiology and survival of colorectal cancer, 24 of 715 cases and 4 of 727 age/sex group matched controls gave a past history of bowel polypectomy (X21 = 17, P less than 0.001, relative risk = 6.37, 95 per cent confidence interval = 2.2-18.6). There was no significant sex or site difference associated with a history of previous polypectomy. These findings are consistent with the view that colorectal polyps are markers of risk (sixfold in the present study) for the subsequent development of colorectal cancer. The data also support the emerging practice that those with adenomatous polyps need regular surveillance of their large bowel as a screening measure.