Long-term effectiveness of faecal immunochemical test screening for proximal and distal colorectal cancers

Area of Science:

• Gastroenterology
• Oncology
• Public Health

Background:

• Population-based screening programs are crucial for early detection of colorectal cancer (CRC).
• The faecal immunochemical test (FIT) is a widely adopted screening tool for CRC.
• Understanding the long-term effectiveness of FIT screening, particularly site-specific outcomes, is essential for optimizing public health strategies.

Purpose of the Study:

• To evaluate the long-term effectiveness of a nationwide, population-based faecal immunochemical test (FIT) screening program for colorectal cancer (CRC).
• To assess the impact of FIT screening on overall and site-specific incidence of advanced-stage CRC and CRC mortality.
• To provide evidence-based policy recommendations for sustainable CRC screening programs.

Main Methods:

• A prospective cohort study involving over 5.4 million Taiwanese individuals invited to biennial FIT screening from 2004-2009, with follow-up until 2014.
• Bayesian Poisson regression models were used to estimate adjusted relative rates (aRRs) for advanced-stage CRC and CRC death.
• Analyses accounted for self-selection factors, including screening and colonoscopy rates, and colonoscopy completeness, alongside demographic features.

Main Results:

• FIT screening significantly reduced the incidence of advanced-stage CRC by 34% (aRR=0.66) and CRC mortality by 40% (aRR=0.60).
• The effectiveness was more pronounced in reducing distal advanced-stage CRCs (aRR=0.61) and associated mortality (aRR=0.56) compared to proximal advanced CRCs (aRR=0.84) and their mortality (aRR=0.72).
• Incidence of advanced-stage CRC decreased from 75.7 to 48.4 per 100,000, and mortality from 41.3 to 20.3 per 100,000 in the screened group.

Conclusions:

• Large-scale, biennial FIT screening is effective in reducing advanced CRC incidence and mortality.
• The study highlights a significant disparity in long-term effectiveness, with greater benefits observed in the distal colon.
• Findings support the implementation of sustainable, population-based FIT screening programs globally and suggest a need to address lower effectiveness in proximal colon screening.