An association between adenomatous polyps of the large bowel and colorectal cancer has been reported, in the absence, however, of population-based estimates of risk.

Subjects with histologically confirmed first diagnosis of large-bowel polyps notified to the population-based Cancer Registry of the Swiss Canton of Vaud (about 600,000 inhabitants) during the calendar period 1989-1990 were actively followed up to the end of 1990 for the subsequent occurrence of malignant neoplasms.

Among 2,496 individuals with intestinal polyps, followed for a total of 10,310 person-years at risk (6,201 among males and 4,109 among females), 150 malignant neoplasms were registered versus 152 expected.

Thus, the standardized incidence ratio (SIR) for all cancers combined was 0.99.