In a randomized controlled trial (RCT) study of 85K Europeans, published this week in the New England Journal of Medicine, colonoscopies were found to reduce incidence of colorectal cancer by only 18 percent—much less than earlier large studies—and have no impact on ten-year colorectal cancer mortality rates. This is the first study to directly compare individuals invited to receive colonoscopies with a control group receiving no cancer screening.
While the study’s findings surprised many researchers, an important caveat to the headline takeaways is that a secondary analysis of study participants who actually completed their colonoscopies found a 50 percent reduction in death, though the decision to accept the invitation likely correlates with other factors that improve mortality outcomes.
The Gist: We were surprised to learn this was the first RCT to assess the effectiveness of colonoscopies—15M of which are performed in the US each year—and which comprise a $36B market. While the study’s results need careful interpretation, it reminds us that much of established medical consensus has yet to be “proven” by rigorous scientific research.
While we don’t expect this study’s results to significantly change colonoscopy recommendations, it does place greater emphasis on the question of value generated by widespread preventative screenings. Colonoscopy will almost certainly remain the gold standard for colon cancer screening in the US, but if these results bear out, other less invasive types of screening, like home-based fecal immunochemical testing, could be viewed as equivalent options and receive more traction.