Organized FIT screening tied to sustained drop in colorectal cancer deaths in Spain's Basque Country

An organized, biennial fecal immunochemical testing (FIT) program launched in 2009 for residents aged 50 to 69 in Spain's Basque Country is associated with a sustained reduction in colorectal cancer mortality through 2024, according to a study published in JAMA Network Open. Researchers led by Luis Bujanda of the University of the Basque Country analyzed mortality data for the region's approximately 2.2 million inhabitants from 2004 to 2024.

Age-standardized colorectal cancer mortality fell from 32.8 deaths per 100,000 population in 2004 to 23.1 per 100,000 in 2024, a 29.6% overall decline. Among the screening-eligible group aged 50 to 69, mortality dropped 50.1%, from 39.7 to 19.8 deaths per 100,000. A significant inflection point appeared in 2012, three years after the program started.

Counterfactual modeling estimated a 46.2% relative reduction in mortality for the 50-to-69 age group compared with projected trends without screening. For individuals aged 70 and older, who were not directly targeted, mortality declined 19.6% from 165.4 to 132.9 per 100,000, corresponding to a 45.4% relative reduction versus projected rates.

During the study period, the program detected 4,892 colorectal cancers, of which 70.8% were diagnosed at stage I or II. The authors state the findings support the long-term benefit of organized FIT-based screening as a public health strategy to reduce colorectal cancer mortality.

The study is observational and cannot prove causation, though the timing of the mortality inflection aligns with screening implementation. Researchers note that mortality reductions in the older, non-targeted group may reflect indirect effects such as increased awareness or opportunistic testing, but the magnitude and timing differ from the screened cohort.