The prevalence of negative fecal occult blood test (FOBT) among colorectal cancer patients in a tertiary care center.

Objectives: Colorectal cancer (CRC) is the third most common cancer worldwide and a leading cause of death. The fecal occult blood test (FOBT) is a widely used initial screening test; however, its results can be influenced by multiple factors. This study aimed to evaluate the prevalence of negative FOBT among patients with CRC and possible etiologies. Methodology: This case-control study included patients aged 50 years and older who were diagnosed with CRC and underwent FOBT. Risk factors and comorbidities were recorded. FOBT results, Colonoscopy findings, tumor location, and type were investigated. Results: A total of 118 patients diagnosed with CRC, who underwent FOBT were included in this study. Of the 118 patients, 63 were males, and 55 were females, with a mean age of 61.3 years and a mean body mass index of 28.87. The most common comorbidity was hypertension (44.9%). Furthermore, 47.5% of the participants had positive FOBT, and 52.5% had negative FOBT. The most common colonoscopy finding was a mass lesion (49%), which was in the rectum (42.4%). Adenocarcinoma was the most common histopathological diagnosis (81.4%). No significant relationship was observed between FOBT results and other variables. Conclusion: More than half of the CRC cases had negative FOBT despite the distal location and type of the tumor. Screening options should be discussed with patients, and further studies are needed to evaluate noninvasive stool-based tests.