Varut Lohsiriwat MD*, Parinya Thavichaigarn MD**, Burin Awapittaya MD***
Affiliation : * Department of Surgery, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok ** Department of Surgery, Pramongkutklao Hospital, Bangkok *** Department of Surgery, Rajavithi Hospital, Bangkok
Background : Colorectal cancer (CRC) screening by guaiac fecal occult blood test (gFOBT) can reduce the
mortality of CRC. The new immunochemical fecal occult blood test (iFOBT) has possibly improved sensitivity
and specificity without any dietary restriction.
Objective : The present study aimed to evaluate the sensitivity, specificity, positive and negative predictive
values of iFOBT for CRC detection compared to the colonoscopic and pathologic findings in known CRC cases.
Materials and Methods : A multicenter prospective study was conducted in three university hospitals in Bangkok,
Thailand, between May and August 2006. Stool samples from 100 histologically-proven CRC patients and 64
control cases with normal colonoscopic findings were collected for iFOBT (OC-Light, Nagase, Singapore)
without dietary restriction.
Results : The results showed the sensitivity, specificity, positive and negative predictive values of iFOBT for
CRC detection to be 91.0% (95% CI: 83.8-95.2), 93.8% (95% CI: 85.0-97.5), 95.8% (95% CI: 89.7-98.4) and
87.0% (95% CI: 77.0-93.0) respectively. The sensitivity for CRC according to Dukes’ stage was 71.4% (Dukes’
A), 88.0% (Dukes’ B), and 96.7% (Dukes’ C or D). The sensitivity was 84.2% for proximal colon and 92.6% for
distal colon and rectum.
Conclusion : The iFOBT revealed high sensitivity, specificity, positive and negative predictive values for CRC
detection without dietary restriction. It should be considered as a noninvasive tool for CRC detection.
Keywords : Immunochemical fecal occult blood test, FOBT, Colorectal cancer, Sensitivity, Specificity, Accuracy
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