The risk of colorectal neoplasia can be different according to the types of family members affected by colorectal cancer.

BACKGROUND AND AIM: A family history of colorectal cancer (CRC) is an important risk factor for CRC, but more detailed data are needed to prepare effective screening guidelines. We aimed to evaluate the risk of colorectal neoplasia (CRN) among individuals with different relatives affected by CRC (the first-degree relatives [FDRs] or the second-degree relatives or the first cousins) and to assess the effects of family histories according to age groups (30-39, 40-49, and ≥ 50 years).

METHODS: A cross-sectional study was performed on 98 562 asymptomatic examinees aged ≥ 30 years who underwent colonoscopy as part of a health checkup.

RESULTS: Mean age of the study population was 41.4 years, and the prevalence of CRN was 15.7%. Participants with ≥ 1 FDRs and ≥ 2 FDRs affected by CRC had a higher risk of CRN than those with no family history of CRC, while those with ≥ 1 second-degree relatives or first cousins affected did not. In the 30-39 and 40-49 years age groups, a family history of CRC in parents was a risk factor for CRN and advanced CRN, but not in siblings. By contrast, in the ≥ 50 age group, participants with affected siblings (reference group) had a significantly higher risk for advanced CRN than those with affected parents (adjusted odds ratio; 95% confidence interval: 0.39; 0.16-0.94 in father and 0.43; 0.18-0.995 in mother).

CONCLUSIONS: The risk of CRN can be different according to the types of family members affected, and the impact of such family histories can be different according to age.