CRC mortality falls by half with fecal screening follow-up

Clinical takeaway: The mortality benefit of stool-based screening rests on what happens after the order. Tracking unreturned kits and getting every positive result to colonoscopy matters most.

Colorectal cancer screening is one of the few interventions in primary care with a plausible path to halving disease-specific mortality. Whether any given practice gets there depends less on which test it uses than on whether patients finish the sequence the test starts.

That distinction now has population-scale evidence behind it: in a system where about seven in 10 returned a kit and more than nine in 10 positives reached colonoscopy, the death rate among screening-age adults fell by half over 21 years.

Previously, a large European randomized trial invited adults to a single colonoscopy and compared them with adults who got no invitation. After 13 years, cancers were less common in the invited group, but CRC deaths were not. No one has yet explained that convincingly. The current analysis looked at the opposite end of the problem: not whether screening was offered but what happened in a system where most patients actually finish the process.

The Basque region of Spain created an opportunity to follow a natural experiment when its colorectal cancer screening program launched in 2009 and reached full coverage by 2014. This gave researchers a rare 21-year window spanning prescreening years, rollout, maturity, and pandemic disruption. Few other fecal immunochemical test (FIT) programs have been followed that long at that scale. Mailed kits arrived on a biennial schedule, positives went directly to colonoscopy, and neither handoff waited on a clinic visit.

Between 2004 and 2024, CRC mortality among adults aged 50 to 69 fell to 19.8 deaths per 100,000 from 39.7. Population-wide, across all ages, it dropped to 23.1 from 32.8. The trend turned in 2012, three years after launch, following a transient mortality rise during early rollout when the program was still surfacing previously undiagnosed cancers. Just over 70% of screen-detected cancers were stage I or II.

This was a retrospective cohort analysis of aggregate registry data on about 2.2 million residents, with rates age-standardized to a European reference population and a break point in the mortality trend identified statistically rather than assumed at the launch year.

The Basque program has already moved past its original age range, starting to extend invitations to adults aged 70 to 74, with first-year results reported in March 2026. Participation ran above 77%, and the CRC detection rate was roughly double that in the 50-to-69 group. US guidance for CRC screening reaches a bit further on both ends of the age spectrum, recommending screening from age 45 through 75.

The Basque analysis "makes a valuable contribution to the evidence that mature FIT programs are delivering substantial reductions in CRC mortality at the population level," writes Uri Ladabaum, MD, MS, of Stanford University School of Medicine, in an invited commentary.

Source: Bujanda L, et al. (2026 Aug 5) JAMA Netw Open. Colorectal Cancer Mortality Following an Organized Fecal Immunochemical Test–Based Screening Program