Annual Scientific Meeting
Introduction: Recent increases in colorectal cancer (CRC) incidence in adults less than 50 years of age have led to more colonoscopies in this age group. As a result, there is an increasing number of adults < 50 with adenomas detected. We used data from the New Hampshire Colonoscopy Registry (NHCR) to explore whether these younger adults with adenomas are at higher risk for future advanced findings than older patients, potentially requiring closer follow-up.
Methods: Our cohort was NHCR participants with at least one adenoma and/or serrated polyp on index exam and a follow-up colonoscopy at least 1 year after the index exam. Outcomes were the absolute and adjusted metachronous risks of advanced adenomas (AA: adenomas >1cm, with villous elements or high-grade dysplasia, or CRC) and large ( >1 cm) serrated polyps (SP). Incomplete exams and patients with IBD or genetic familial syndromes were excluded. We present absolute risk and adjusted risks from a logistic regression model stratified by age at index colonoscopy (< 40, 40-49, 50-59, and 60+ (ref)). Covariates include findings on previous and index colonoscopy, sex, smoking, body mass index (BMI), time to follow-up (months), bowel preparation quality, and family history of CRC.
Results: Time to follow-up did not vary with age in our sample of 10,116 adults (Table 1). Absolute risk for metachronous AA was lower for younger patients (p < 0.0001) (Table 1), with the lowest risk in patients < 40, similar risks in the 40-49 and 50-59 groups, and highest risk in patients >60. Adjusting for covariates did not change findings (p=0.003). Because younger adults were less likely to have index AAs, we performed a sensitivity analysis, excluding index exams with AAs, and observed no changes in results (p=0.003). The metachronous risk for large SPs was not significantly associated with age (Table 2).
Discussion: Younger adults with index adenomas have a lower risk for metachronous AAs than patients >50. These data suggest that younger adults are not at higher risk for metachronous advanced neoplasia than older adults. The data also suggest that surveillance intervals recommended by current guidelines for adults > 50 years may be safe to apply to younger adults.