Screening colonoscopy may lead to a lower lifetime incidence of colorectal cancer and death by half or more, according to a study published online ahead of print in the June 16 issue of JAMA. 

Reinier G.S. Meester, MSc, and colleagues analyzed more than 57,000 screening colonoscopies, finding that higher adenoma detection rates (ADRs) may be associated with up to 50% to 60% lower lifetime incidence of and death from colorectal cancer without higher overall costs, despite a higher number of colonoscopies and potential complications.

The effectiveness of screening colonoscopy depends on the quality of the examination, which is measured by ADRs. This rate reflects the proportion of a physician’s screening colonoscopies that detect at least 1 histologically confirmed adenoma and varies widely among physicians who conduct the examination, the authors wrote. The researchers used microsimulation modeling to estimate the benefits and risks of screening colonoscopy at different ADRs among 57,588 patients examined by 136 physicians. No screening was compared with screening colonoscopy according to five ADR quintiles. The ADRs ranged from 7.4% to 53%, with the rates increasing from quintile 1 to quintile 5. 

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Among unscreened patients, the model estimated that the lifetime risk for colorectal cancer was 34.2 per 1,000 persons, and the lifetime risk for death from colorectal cancer was 13.4 per 1,000 persons. For patients who would be screened, the model found the risks were inversely related to the ADR. For instance, in quintile 1, the lifetime risk for colorectal cancer was 26.6 per 1,000 persons and was lower for subsequent quintiles, with a risk of 12.5 per 1,000 persons in quintile 5. For every five-point increase in ADR, the risks were 11% to 13% lower, for an overall difference of 53% to 60% between quintile 1 and 5.