Comparison between an immunochemical fecal occult blood test and a Guaiac based fecal occult blood test in detection of adenomas and colorectal cancer

Abstract

Colorectal cancer (CRC) is the third most commonly diagnosed cancer worldwide. Brazil does not have an official well established program for screening colorectal cancer. The aim of this study was to compare Guaiac Based Fecal Occult Blood Test (G-FOBT) to a kind of an Immunochemical Fecal Occult Blood Test (I-FOBT), in search of cancer or advanced adenoma. Prospective and cross-sectional study. Asymptomatic and average-risk individuals (n = 1500) aged from 50 to 75 years old were invited to participate in the study. The primary endpoint was positivity rate and the secondary endpoints were adherence rate and significant endoscopic findings. All participants received both tests with follow-up colonoscopy if either test was positive. Adherence rate of G- FOBT was 756/1500 (50.4%) while for I- FOBT it was 960/1500(64%). The positivity ratio in the I- FOBT was 94/960 (9.8%) and in the G-FOBT was 20/771 (2.6%). The Positive Predict Value (PPV) for the I- FOBT counted 16/77 (21.0%) while for the G- FOBT it was 6/18 (33.0%), considering significant lesions. Regarding the colorectal cancer findings, the detection in the colonoscopy guided from the positivity of fecal occult blood tests was 5/77 (6.5%) in I- FOBT and 2/18 (11.1%) on the G- FOBT. The positivity, the adherence rate and the capacity to detect significant lesions were higher in I-FOBT. Considering the findings of the study we could conclude that I-FOBT was superior to G- FOBT. This study was reviewed and approved by the Institutional Review Board of A.C.Camargo Cancer Center, São Paulo, Brazil, number: 1877/14.