August 21, 2017
Contrary to current guidelines, new research published in Annals of Internal Medicine suggests that colorectal cancer screening with flexible sigmoidoscopy reduces risk for death, indicating that existing recommendations need to be reassessed.
“The 2016 U.S. Preventive Services Task Force (USPSTF) evidence report on colorectal cancer screening concluded that no colorectal cancer screening methods reduce all-cause mortality,” Andrew W. Swartz, MD, from the Yukon-Kuskokwim Delta Regional Hospital in Alaska, and colleagues wrote. “This conclusion was partially based on a meta-analysis of four randomized trials that compared flexible sigmoidoscopy screening with no screening. The meta-analysis aggregated results from the two age cohorts of one of the trials — the NORCCAP (Norwegian Colorectal Cancer Prevention) study — as if these cohorts were a single trial. Aggregation of outcomes that have markedly different event rates, screening-control ratios, or both can create a Simpson paradox.”