Family history of colorectal adenomatous polyps as a risk factor for colorectal cancer

The aim of this study was to evaluate the risk of common colorectal cancer among first-degree relatives of patients with colorectal adenomatous polyps . In a population screening programme, 59 406 subjects underwent an immunoc hemical faecal occult blood test. In a medical check-up-based cross-section al study, 6139 subjects had a colonoscopic examination. They were divided i nto two groups, according to the results of a questionnaire on family histo ry of colorectal adenomatous polyps, and the detection rates for colorectal cancer were compared in the groups positive or negative for a family histo ry of colorectal adenomatous polyps. In the screening programme-based cross -sectional study, the detection rate for colorectal cancer was 0.57% (95% c onfidence interval (CI): 0.38-0.76) and 0.15% (95% CI: 0.12-0.18) in subjec ts with and without a family history of colorectal adenomatous polyps, resp ectively, showing a significant difference in the detection rate for colore ctal cancer between the two groups (P < 0.05). In the medical check-up-base d cross-sectional study, the detection rate for colorectal cancer was 2.31% (95% CI: 1.15-3.47) and 0.53% (95% CI: 0.34-0.72) in subjects with and wit hout a family history of colorectal adenomatous polyps, respectively, indic ating a significant difference between the two groups (P < 0.05). These fin dings indicate that first-degree relatives of patients with colorectal aden omatous polyps have an elevated risk for common colorectal cancer, and that people with a family history of colorectal adenomatous polyps should be co nsidered as a priority group for colorectal cancer screening. (C) 2000 Else vier Science Ltd. All rights reserved.