The incidence rate of familial adenomatous polyposis. Results from the Danish Polyposis Register.

Based on the Danish Polyposis Register epidemiological calculations on familial adenomatous polyposis (FAP) were carried out. The mean annual incidence was 1.85 x 10(-6) during the years 1971-1992, and the prevalence increasing to about 32 x 10(-6) at the end of 1992. FAP patients constituted a decreased percentage of all Danish patients with colorectal cancer (0.07% in 1980-1992). The completeness of registration was 97% in 1983-1992. The results are similar to Finnish estimates based on the same direct method of calculation, and as both series are based on almost complete national polyposis registration in well-registered populations we regard our results to be close to the true incidence rate.