Young adults and metachronous neoplasia: risks for future advanced adenomas and large serrated polyps compared with...

Recent increases in colorectal cancer (CRC) incidence in adults younger than 50 years of age have led to more colonoscopies in this age group. As a result, there may be an increasing number of adults <50 years old with polyps detected. There is concern that younger adults may require closer follow-up. Our goal was to use data from the New Hampshire Colonoscopy Registry (NHCR) to examine the risk for metachronous advanced adenomas (AAs) and large (>1 cm) serrated polyps in younger versus older adults who return for a follow-up colonoscopy.

Our cohort consisted of NHCR participants with at least 1 polyp on index examination and a follow-up colonoscopy at least 1 year after the index examination. Outcomes were the risks for metachronous AAs (adenomas ≥1 cm, with villous elements or high-grade dysplasia, or CRC) and large (≥1 cm) serrated polyps. 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+ [reference]). Covariates included index findings, endoscopist adenoma detection rates, sex, smoking, body mass index, follow-up time (months), bowel preparation quality, and family history of CRC.

In our sample of 12,380 adults, absolute risk for metachronous AA was lower for younger patients than for patients aged ≥60. After adjusting for covariates, when comparing with the 60+ group (reference), the lowest risk was observed in those younger than 40 years (odds ratio, .19; 95% confidence interval, .05-.80). Of note, similar risks were observed in the 40 to 49 age group (odds ratio, .61; 95% confidence interval, .41-.92) and 50 to 59 age group (odds ratio, .71; 95% confidence interval, .58-.86). The risk for large metachronous serrated polyps was not associated with age.

Younger adults aged <40 with index adenomas had a lower risk for metachronous AAs than those aged ≥60. The 40- to 49-year age group was found to have metachronous risk similar to the 50- to 59-year age group, with both less than the ≥60 age group. These data suggest that current surveillance interval guidelines for patients aged ≥50 years may appropriately be used with younger adults.