Rescreening interval after normal colonoscopy may be too short

Last Updated: 2018-12-17

By Megan Brooks

NEW YORK (Reuters Health) - Evidence to support a 10-year rescreening interval after a normal colonoscopy is limited and may be worth revisiting, according to results of a large retrospective cohort study.

The study, online today in JAMA Internal Medicine, found that a negative colonoscopy result in average-risk is associated with a low risk of colorectal cancer and related deaths for more than 12 years.

"Many patients ask when they should come back after a normal colonoscopy. Although our guidelines recommend a 10-year re-screening interval after a normal colonoscopy, there is little evidence to inform this recommendation," first author Dr. Jeffrey Lee from the Division of Research, Kaiser Permanente Northern California in Oakland told Reuters Health.

"Our findings suggest that physicians and patients should feel confident following the guideline-recommended 10-year re-screening interval after a normal colonoscopy. Our study also provides additional data for guideline developers on the possibility of extending the re-screening interval, given that colorectal cancer risk and related deaths remained reduced for more than 12 years after a normal colonoscopy," Dr. Lee said by email.

The analysis included more than 1.2 million average-risk, screen-eligible adults (mean age 55.6; 49% men), who contributed more than 9.3 million person-years of follow-up.

Compared with unscreened adults, those with a negative (normal) colonoscopy result had a reduced risk of colorectal cancer and related deaths during the more than 12-year follow-up period.

Although reductions in risk were attenuated with increasing years of follow-up, at 10 years (the current guideline-recommended rescreening time) there was a 46% lower risk of colorectal cancer (hazard ratio, 0.54; 95% confidence interval, 0.31 to 0.94) and 88% lower risk of related deaths (HR, 0.12; 95% CI, 0.02 to 0.82).

"In separate analyses, reduced risks of colorectal cancer were observed by colon site and cancer stage, although 95% CIs were wider and included the null in the later years," the authors report.

These findings, they say, have policy implications on the timing of rescreening after a negative colonoscopy result.

"The current guideline-recommended 10-year rescreening interval is not based on a pre-determined risk threshold, and while we observed a reduced risk of colorectal cancer and related deaths throughout the more than 12-year follow-up period, an examination of absolute risk (incidence) could provide another justification for the timing for rescreening," they write.

"Additional research is needed to evaluate the costs and benefits of earlier vs later rescreening, optimal rescreening tests following a negative colonoscopy result (eg, another colonoscopy vs annual fecal immunochemical testing), and whether the benefits of rescreening vary between subgroups," they conclude.

The authors note that one other study evaluated risk of colorectal cancer annual since a negative colonoscopy and found significant reductions up to 14 years. (https://bit.ly/2ChzQTT)

SOURCE: https://bit.ly/2ChhphY

JAMA Intern Med 2018.