Comparison of One versus Two Fecal Immunochemical Tests in the Detection of Colorectal Neoplasia in a Population-Based Colorectal Cancer Screening Program

Abstract EN

Objective.

To determine the positive predictive value (PPV) of two versus one abnormal FIT in the detection of colorectal neoplasia in a Canadian population.

Methods.

Three communities enrolled in a colorectal cancer (CRC) screening pilot program from 01/2009 to 04/2013 using 2 FITs.

Data collected included demographics, colonoscopy, pathology, and FIT results.

Participants completed both FITs and had one positive FIT and colonoscopy.

PPV of one versus two abnormal FITs was calculated using a weighted-generalized score statistic.

A two-sided 5% significance level was used.

Results.

1576 of 17,031 average-risk participants, 50–75 years old, had a positive FIT.

Colonoscopy revealed 58 (3.7%) cancers, 419 (31.6%) high-risk polyps, and 374 (23.7%) low-risk polyps as the most significant lesion.

PPV of one versus two positive FITs for cancer, high-risk polyps, and any neoplasia were 1% versus 8%, 20% versus 40%, and 48% versus 67%, respectively (p value < 0.0001).

When the first FIT was negative, the second positive FIT detected 7 CRCs and 98 high-risk polyps.

Conclusions.

PPV of two positive FITs is superior to one positive FIT for CRC and high-risk polyps.

The added value of the second FIT was 12% of total CRCs and 23% of total high-risk polyps.