The long-term risks of colorectal cancer (CRC) and CRC-related death following adenoma
removal are uncertain. Data are needed to inform evidence-based surveillance guidelines,
which vary in follow-up recommendations for some polyp types. Using data from a large,
community-based integrated health care setting, we examined the risks of CRC and related
death by baseline colonoscopy adenoma findings. Participants at 21 medical centers
underwent baseline colonoscopies from 2004 through 2010; findings were categorized
as no adenoma, low-risk adenoma, or high-risk adenoma. Participants were followed
until the earliest of CRC diagnosis, death, health plan disenrollment, or December
31, 2017. Risks of CRC and related deaths among the high- and low-risk adenoma groups
were compared with the no adenoma group using Cox regression adjusting for confounders.
Among 186,046 patients, 64,422 met eligibility criteria (54.3% female; mean age, 61.6±7.1
y; median follow-up time, 8.1 y from the baseline colonoscopy). Compared with the
no-adenoma group (45,881 patients), the high-risk adenoma group (7563 patients) had
a higher risk of CRC (hazard ratio [HR], 2.61; 95% CI, 1.87–3.63) and related death
(HR, 3.94; 95% CI, 1.90–6.56), whereas the low-risk adenoma group (10,978 patients)
did not have a significant increase in risk of CRC (HR, 1.29; 95% confidence interval,
0.89–1.88) or related death (HR, 0.65; 95% CI, 0.19–2.18). With up to 14-years of
follow-up, high-risk adenomas were associated with an increased risk of CRC and related
death, supporting early colonoscopy surveillance. Low-risk adenomas were not associated
with a significantly increased risk of CRC or related deaths. These results can inform
current surveillance guidelines for high- and low-risk adenomas. With up to 14-years
of follow-up, high-risk adenomas were associated with an increased risk of colorectal
cancer and related deaths. Low-risk adenomas were not associated with a significantly
increased risk of colorectal cancer or related deaths.