FIT-Based Screening Steadily Cut Colorectal Cancer Deaths in Spain, 20-Year Data Show

A Two-Decade Look at Colorectal Cancer Deaths in the Basque Country

A 20-year analysis covering more than 2 million residents of Spain’s Basque Country shows that introducing a biennial fecal immunochemical test (FIT) screening program was followed by a sustained decline in colorectal cancer (CRC) mortality. Between 2004 and 2024, age-standardized CRC mortality fell from 32.8 to 23.1 deaths per 100,000 population—a drop of nearly 30%—with the most dramatic improvement among the target age group of 50 to 69, where deaths halved. The study, published in JAMA Network Open, identified an inflection point around 2012, roughly three years after the organized program launched in 2009.

Counterfactual modeling indicated that without the screening program, mortality would have followed a much higher trajectory. The researchers estimated a 41.7% relative reduction in CRC mortality overall compared with projected trends, and a 46.2% reduction in the 50–69 age group. Even among residents aged 70 and older—outside the program’s initial target—mortality was 45.4% lower than expected, a finding the authors attribute to spill-over effects and growing awareness.

Participation in the program remained remarkably high: median uptake of invitations rose from 67.2% in the early years to over 73% by 2015–2019, and held near 71% during the COVID-19 period. The program’s design, built on centralized electronic health records that automatically exclude ineligible individuals, helped achieve colonoscopy completion rates above 91% after an abnormal FIT result. Seven in ten screen-detected cancers were caught at stage I or II, when treatment is far more effective.

What the Spanish Findings Mean for FIT Screening—and the NordICC Puzzle

The Basque Model: High Participation, High Impact

The Basque screening program stands out for its operational excellence. Invitations are systematically sent to asymptomatic 50–69-year-olds using a central registry, minimizing administrative leakage. Participation rates exceed the 65–70% often cited as a threshold for population-level benefit, and the swift colonoscopy follow-up for positive FITs ensures that early-stage cancers are removed or treated promptly. The program’s performance—72% invitation completion, >91% colonoscopy adherence—provides a real-world benchmark that many health systems still struggle to match.

Reconciling the NordICC Outlier

The encouraging numbers land amid persistent questions raised by the NordICC trial, which randomized over 80,000 participants to colonoscopy invitation versus usual care and found a significant drop in CRC incidence but no mortality benefit at 13 years. In an invited commentary, Stanford’s Uri Ladabaum noted that this Spanish study strengthens the case that mature FIT programs deliver substantial population-level mortality reductions, contrasting sharply with NordICC’s puzzling result. He stressed that “it is critical to arrive at a satisfactory understanding” of why the colonoscopy trial diverged from decades of fecal occult blood and sigmoidoscopy evidence. The current analysis does not resolve the NordICC conundrum, but it adds weight to the argument that—far from questioning whether screening is worthwhile—the focus should be on optimizing delivery of this proven intervention.

Beyond the Target Age

The clear mortality decline among over-70s, a group outside the formal invitation window, suggests that organized programs generate broader behavioral and clinical effects. The authors propose that risk-adapted screening, potentially extending to older adults or incorporating other modalities, could yield further gains. With CRC incidence rising in younger populations, the age extension recommended by the U.S. Preventive Services Task Force (starting at 45) aligns with the study’s implication that well-run FIT programs can drive down cancer deaths across a wider age band.

For Health Systems: Translating the Basque Model into Practice

• Replicate the Basque infrastructure: Invest in centralized electronic health records that automatically identify eligible individuals and track invitation-to-colonoscopy pathways to achieve participation above 70% and post-FIT colonoscopy rates exceeding 90%.
• Don’t let NordICC stall progress: The NordICC trial’s mortality null result should not be used to question FIT’s value. Policymakers should view the totality of evidence—including this 20-year data—as confirmation that organized FIT screening reliably reduces CRC deaths when implemented with high adherence.
• Consider expanding the age window: Given the mortality benefit observed in the over-70s and rising early-onset CRC, health systems can evaluate risk-based screening that starts at 45 and continues beyond age 69, with intervals and modalities tailored by risk level.
• Monitor program fidelity, not just coverage: Keep a close eye on the proportion of screen-detected cancers diagnosed at early stages (in the Basque program, 70.8% at stage I/II) and aim to recover participation rates quickly after disruptions like pandemics—the program’s bounce-back to 71% during COVID-19 shows it can be done.