Cancer Incidence and Mortality Risk After Index Colonoscopies Showing Low-Risk Adenomas, High-Risk Adenomas, or No Adenomas

Colorectal

Douglas K. Rex, MD, MASGE reviewing Duvvuri A, et al. Gastroenterology 2021 Jan 28.

Postpolypectomy surveillance recommendations are based on observational studies, often using advanced adenomas at follow-up as their primary outcome.

A new meta-analysis focused on the risk of incident cancer and related mortality reviewed 12 studies with 510,019 patients. Colorectal cancer incidence per 10,000 person-years was slightly higher in those with low-risk adenomas (1-2 adenomas <10 mm with tubular histology and only low-grade dysplasia) than no adenomas, with a statistically significant odds ratio (OR) of 1.26 (95% confidence interval [CI], 1.06-1.5). For those with high-risk adenomas compared to those with no adenomas, the odds ratio for cancer was 2.92 (95% CI, 2.31-3.69). Cancer-related mortality in those with low-risk adenomas compared to no adenomas was not statistically significant (OR, 1.15; 95% CI, 0.76-1.74) but was higher in those with high-risk adenomas (OR, 2.69; 95% CI, 1.87-3.87). Both cancer incidence and mortality were also significantly higher in those with high-risk adenomas compared with low-risk adenomas.

The authors argue that these data indicate that surveillance intervals in those with low-risk adenomas should be the same as those with no adenomas.

Comment:

The U.S. Multi-Society Task Force (MSTF) on Colorectal Cancer recommends that patients with low-risk adenomas undergo surveillance at 7 to 10 years. The MSTF guidelines can be considered cautious and conservative compared to current guidelines outside the U.S., which often recommend colonoscopy at 10 years or no surveillance for those with low-risk adenomas. The large problem in understanding the available observational studies is that those with low-risk adenomas have often undergone significantly more colonoscopies during the follow-up interval than those with no adenomas. This limitation of observational studies and meta-analyses of those studies was a primary reason for the MSTF’s cautious recommendation of surveillance at 7 to 10 years rather than 10 years for those with low-risk adenomas.

Note to readers: At the time we reviewed this paper, its publisher noted that it was not in final form and that subsequent changes might be made.

Douglas K. Rex, MD, MASGE

Bio and Disclosures

Citation(s):

Duvvuri A, Chandrasekar VT, Srinivasan S, et al. Risk of colorectal cancer and cancer related mortality after detection of low-risk or high-risk adenomas, compared with no adenoma, at index colonoscopy: a systematic review and meta-analysis. Gastroenterology 2021 Jan 28. (Epub ahead of print) (https://doi.org/10.1053/j.gastro.2021.01.214)