Accuracy of Self-Checked Fecal Occult Blood Testing for Colorectal Cancer in Thai Patients


Purpose: Colorectal cancer (CRC) screening with fecal occult blood testing (FOBT) has been associatedwith a reduction in CRC incidence and CRC-related mortality. However, a conventional FOBT requires stoolcollection and handling, which may be inconvenient for participants. The EZ-DetectTM (Siam PharmaceuticalThailand) is a FDA-approved chromogen-substrate based FOBT which is basically a self-checked FOBT (nostool handling required). This study aimed to evaluate the accuracy of EZ-Detect for CRC detection.
Methods:This prospective study was conducted in the Faculty of Medicine, Siriraj Hospital, Bangkok, Thailand betweenNovember 2013 and May 2014. Some 96 patients with histologically-proven CRC and 101 patients with normalcolonoscopic findings were invited to perform self-checked FOBT according to the manufacturer’s instructions.Results were compared with endoscopic and pathologic findings. Sensitivity, specificity, positive predictive value(PPV), and negative predictive value (NPV) for CRC detection were calculated.
Results: The present studyrevealed the sensitivity, specificity, PPV and NPV of this self-checked FOBT for CRC detection to be 41% (95%CI: 31-51), 97% (95% CI: 92-99), 93% (95% CI: 81-98) and 63% (95% CI: 55-70), respectively. The overallaccuracy of the self-checked FOBT for identifying CRC was 70%. The sensitivity for CRC detection based on7th AJCC staging was 29% for stage I, 32% for stage II and 50% for stage III/IV (P=0.19). The sensitivity was33% for proximal colon and 42% for distal colon and rectal cancer (P=0.76). Notably, none of nine infiltrativelesions gave a positive FOBT.
Conclusions: The self-checked FOBT had an acceptable accuracy of CRC detectionexcept for infiltrative tumors. This home-administrated or ‘DIY’ do-it-yourself FOBT could be considered asone non-invasive and convenient tool for CRC screening.