Negative Screening Colonoscopy May Reduce CRC Incidence, Mortality

Just one colorectal cancer (CRC) screening colonoscopy with no neoplastic findings is associated with substantial reductions in incidence and mortality rates among average-risk patients—as long as the colonoscopy is of high quality—according to new data.

In an observational study that followed 165,887 patients for up to 17.4 years, the research team measured standardized incidence ratios (SIRs) and standardized mortality ratios (SMRs) of CRC following a single negative screening colonoscopy. The researchers found that in patients aged 50 to 66 years who were at average risk of CRC, the incidence of CRC was 72% lower and the risk of death from CRC was 81% lower than the general population.

The key qualifier was the quality of the colonoscopy. The researchers defined a high-quality colonoscopy as one that included a complete examination and adequate bowel preparation, and was performed by an endoscopist with an adenoma detection rate of 20% or greater. High-quality examinations resulted in a 2-fold lower rate of CRC (SIR, 0.16 [CI, 0.13-0.20]) and mortality (SMR, 0.10 [CI, 0.06-0.14]) than low-quality examination (SIR, 0.32 [CI, 0.29-0.35]; SMR, 0.22 [CI, 0.18-0.25]).

Current guidelines that call for screening colonoscopies to be performed at 10-year intervals among patients at average risk of CRC are based on estimates of the time required for an adenoma to develop into carcinoma. The results of this study can be interpreted to support the safe extension of intervals between screening colonoscopies in average-risk patients.

However, the researchers concluded that, “Only high-quality colonoscopy yielded profound and stable reductions in CRC incidence and mortality throughout the entire follow-up.”

—Rebecca Mashaw

Reference:

Pilonis ND, Bugajski M, Wieszczy P, et al. Long-term colorectal cancer incidence and mortality after a single negative screening colonoscopy. Ann Intern Med. Published online May 26, 2020. https://doi.org/10.7326/M19-2477