Effect of family history on detection of adenomas and sessile serrated lesions in individuals aged 40s

BACKGROUND According to the guidelines in the United States, individuals with a family history of colorectal cancer should be screened at the age of 40 years. Data on the prevalence of adenomas and sessile serrated lesions (SSLs) in individuals aged 40-49 years in Japan are lacking. AIM To investigate the effect of family history on the detection of adenomas and SSLs during colonoscopy in Japan. METHODS This retrospective, single-center cohort study included individuals aged 40-79 years who underwent colonoscopy by expert endoscopists with an adenoma detection rate (ADR) ≥ 40% between 2021 and 2024. The ADR and adenoma plus SSL detection rate (ASDR) were investigated according to age. Multivariable analyses were performed to examine the effects of first-degree family history of colorectal cancer, fecal immunochemical test, and sex on the ADR and ASDR for each age group. A binomial logistic regression model was used. RESULTS In 10248 participants, the overall ADR and ASDR were 53.6% and 59.1%, respectively. The ADR and ASDR increased with age. Among 2317 participants aged 40-49 years, the presence of a family history significantly increased the ADR (47.6% vs 38.2%). The odds ratio of a family history for the ADR adjusted by sex and fecal immunochemical test was 1.59 (95% confidence interval: 1.13-2.25). In contrast, there was no significant association between the ADR and family history in participants aged 50-59, 60-69, and 70-79 years. Similarly, a family history significantly increased the ASDR (58.0% vs 43.7%) in participants aged 40-49 years. The odds ratio of a family history for the ASDR was 1.92 (95% confidence interval: 1.36-2.71). CONCLUSION Participants with a family history exhibited significantly elevated ADR (47.6%) and ASDR (58.0%), in their 40s. Individuals with a family history should initiate colonoscopy at 40 years old.