Prevalence of family history of colorectal cancer in the general population

Background: Robust estimates of the prevalence of a family history of colorectal cancer in the general population are essential to inform planning of provision for colonoscopic surveillance and for clinical genetics services. However, there is a paucity of high-quality data.

Methods: Computerized record linkage was used to assess systematically the family history of 160 cancer-free community subjects and thereby provide prevalence data that are independent of participant recall. The data set comprised 2664 first- and second-degree relatives of study subjects, with 148 068 years at risk.

Results: Of people in the 30-70 years age range, 9.4 (95 per cent confidence interval (c.i.) 5.8 to 14.9) per cent had a first-degree relative affected by colorectal cancer, and 28.8 (95 per cent c.i. 22.3 to 36.2) per cent had an affected first- or second-degree relative. Between 0 and 3.1 per cent of study subjects merited colonic surveillance, depending on the stringency of the guidelines used.

Conclusion: An appreciable proportion of the general population has a relative affected by colorectal cancer, sufficient to merit screening under certain criteria. In the absence of good-quality evidence supporting colonoscopic surveillance in groups at moderate risk, these data directly inform the planning of services for people with a family history of colorectal cancer. However, the clinical risk and financial implications of screening should be taken into account.