Correlating Quantitative Fecal Immunochemical Test Results with Neoplastic Findings on Colonoscopy in a Population-Based Colorectal Cancer Screening Program: A Prospective Study

Background and Aims. The Canadian Partnership Against Cancer (CPAC) recommends a fecal immunochemical test- (FIT-) positive predictive value (PPV) for all adenomas of ≥50%. We sought to assess FIT performance among average-risk participants of the British Columbia Colon Screening Program (BCCSP). Methods. From Nov-2013 to Dec-2014 consecutive participants of the BCCSP were assessed. Data was obtained from a prospectively collected database. A single quantitative FIT (NS-Plus, Alfresa Pharma Corporation, Japan) with a cut-off of ≥10 μg/g (≥50 ng/mL) was used. Results. 20,322 FIT-positive participants underwent CSPY. At a FIT cut-off of ≥10 μg/g (≥50 ng/mL) the PPV for all adenomas was 52.0%. Increasing the FIT cut-off to ≥20 μg/g (≥100 ng/mL) would increase the PPV for colorectal cancer (CRC) by 1.5% and for high-risk adenomas (HRAs) by 6.5% at a cost of missing 13.6% of CRCs and 32.4% of HRAs. Conclusions. As the NS-Plus FIT cut-off rises, the PPV for CRC and HRAs increases but at the cost of missed lesions. A cut-off of ≥10 μg/g (≥50 ng/mL) produces a PPV for all adenomas exceeding national recommendations. Health authorities need to take into consideration endoscopic resources when selecting a FIT positivity threshold.