Colorectal cancer risk in first-degree relatives of patients with colorectal adenomatous polyp

Background/Aims: To evaluate any risk of colorectal cancer in first-degree relatives of patients with colorectal adenomatous polyp. Methodology: In a screening program-based cross-sectional study, 44821 subjects received an immunochemical fecal occult blood test using a 2-consecutive-day method. They were divided into two groups, according to the results of a self-completed questionnaire on family history of colorectal adenomatous polyps, and the positivity rate of an immunochemical fecal occult blood test as well as the positive predictive value for colorectal cancer were determined in these two groups. Results: The fecal occult blood test was positive in 8.5% of subjects with family history and in 4.8% of subjects without family history, and the positive predictive value for colorectal cancer was 6.8% and 2.4% in subjects with and without family history of colorectal adenomatous polyps, respectively, indicating a significant difference in the positivity rate of the fecal occult blood test (P<0.01) as well as the positive predictive value for colorectal cancer (P<0.05) between these two groups. Conclusions: These results show that first-degree relatives of patients with colorectal adenomatous polyp have an increased risk for colorectal cancer, and that the subjects with family history of colorectal adenomatous polyps as well as cancers should be considered as a priority group for prevention of colorectal cancer.