Association between family history of colorectal cancer and the risk of metachronous colorectal neoplasia following polypectomy in patients aged <50years

Background and AimThe relationship between a family history of colorectal cancer (CRC) and the risk of metachronous colorectal neoplasia (CRN) following polypectomy remains unknown. We aimed to compare the risk of metachronous CRN according to CRC family history in groups of patients aged <50 and 50years. MethodsWe studied patients who underwent 1 adenoma removal between 2010 and 2014 and follow-up surveillance colonoscopic examinations until 2017. ResultsAmong the 9866 patients studied, 544 (5.5%) had 1 first-degree relatives (FDRs) affected by CRC. In patients aged <50years (n=7787), as compared with having no family history of CRC, a positive family history in any FDR (hazard ratio [HR] 1.37, 95% confidence interval [CI] 1.16-1.62), a father (HR 1.35, 95% CI 1.09-1.68), or a mother (HR 1.32, 95% CI 1.005-1.74) was associated with an increased risk of metachronous CRN after adjusting for confounding factors. However, in patients aged 50years (n=2079), there was no significant association between having an FDR with CRC and the risk of metachronous CRN. For metachronous advanced CRN, the association between its risk and family history of CRC was not observed in either the <50years or 50years of age group. ConclusionsHaving an FDR with CRC at a young age (<50years) appears to be closely related to the risk of metachronous CRN. However, considering that the risk of metachronous advanced CRN did not depend on CRC family history, the interval of post-polypectomy surveillance colonoscopy may not need to be adjusted depending on CRC family history.