Three-year risk of colorectal cancer by faecal haemoglobin concentration in subjects with a negative FIT.

INTRODUCTION AND AIM: To evaluate whether a risk-stratified colorectal cancer (CRC) screening approach based on a single faecal immunochemical test (FIT) performed better than one using two consecutive tests. METHODS: Approximately 420,000 negative FIT results (positivity cut-off: 20 µg faecal haemoglobin, f-Hb/g) were collected between 2000 and 2015 within the Florence screening program. RESULTS: The 3-year CRC risk was 15.9‰ in individuals with 15-20 µg/g on a single test, and 9.36‰ for those with a cumulative f-Hb concentration of 20-40 µg/g across two tests. DISCUSSION: The two-tests approach showed lower discriminatory capacity in identifying the highest-risk subgroup compared to a single test. Screenees with 15-20 µg/g accounted for <1%, but faced a significantly increased 3-year CRC risk. CONCLUSION: While increasing screening intensity would require more colonoscopies, extending the screening interval for individuals <60 years with undetectable f-Hb, could allow for the reallocation of colonoscopy resources.