Impact of family history of colorectal cancer on age-specific prevalence of colorectal neoplasia

Background and Aim: There are no established guidelines on screening strategies for persons with a family history of colorectal cancer (CRC) in Korea. We aimed to evaluate the age-specific risk of colorectal neoplasia according to family history of CRC. Methods: Participants who underwent screening colonoscopy were included. Age-specific prevalence of non-advanced adenoma (NAA) and advanced colorectal neoplasia (ACRN) was calculated according to family history of CRC. Results: Among 35 997 participants, 1339 (3.7%) had a family history of CRC in first-degree relatives. A family history of CRC was an independent risk factor for NAA (adjusted odds ratio [AOR] 1.33, 95% confidence interval [CI] 1.16–1.52). In the subgroup analysis by age, family history of CRC was a risk factor for NAA in the 50–59 and ≥ 60 years groups (AOR [95% CI]: 1.42 [1.04–1.91] and 2.33 [1.34–4.09], respectively), but not in the 30–39 and 40–49 years groups. In the curve of age-specific prevalence of NAA, the gap of the prevalence between the family history and non-family history groups began to widen after the mid-50s. In cases of ACRN, a family history of CRC was not a risk factor in the entire age group (AOR 1.16, 95% CI 0.75–1.70). In the curve of age-specific prevalence of ACRN, however, the gap of the prevalence between the family history and non-family history groups began to widen after the early 60s. Conclusion: Although a family history of CRC is a risk factor for NAA, it may affect NAA development from the mid-50s and ACRN development from the early 60s.