Prevalence of Abnormal Colonoscopic Findings in the Colorectal Cancer Screening Program with Fecal Immunochemical Test in Average Risk Individuals

Abstract

Abstract Background: The fecal immunochemical test (FIT) is a stool-based noninvasive test for colorectal cancer (CRC) screening. We aimed to evaluate the colonoscopy results in a population-based CRC screening of average-risk asymptomatic individuals with a positive FIT. Methods: We conducted a cross-sectional study involving 7947 individuals aged 50 to 69 years from 22 primary health care centers. Demographic data were extracted from the primary health care database called 'NAB.' All eligible participants were provided with FIT kits, and those with positive FIT results were referred for colonoscopy. We evaluated the pathologies identified during abnormal colonoscopies. Findings: Our study enrolled 7175 individuals with a mean (SD) age of 58.45 (5.45), of whom 4607 (64.2%) were female and 6226 (86.8%) were married. Out of the participants, 549 individuals tested positive for FIT, yielding a FIT positivity rate of 7.65%. The participation rate for colonoscopy was 55.56% (n=305), and among these, 87 patients had abnormal findings. Among all polyps, adenomas and hyperplastic polyps had higher rates compared to other types (49.48% and 21.64%, respectively). The majority of polyps were found in the rectum and sigmoid colon (73.3%). We observed that 11 patients had CRC based on colonoscopy findings. Abnormal colonoscopy findings were significantly higher in men (P < 0.001, OR=2.25) and in older patients (P=0.015, OR=1.57). Additionally, urban living was identified as a risk factor for colorectal pathologies (OR=2.30). Conclusion: Based on the data obtained in this study, FIT emerges as a suitable tool for colorectal cancer screening. Given its effectiveness in detecting precancerous lesions and CRCs, patients can greatly benefit from FIT for the prevention and early treatment of CRC. Furthermore, considering the higher incidence of abnormal colonoscopy findingsin men and older patients, CRC screening using FIT can significantly reduce the prevalence of colorectal neoplasia in these groups. Nevertheless, to comprehensively evaluate the quality of FIT tests for CRC screening in Iran, further studies with larger sample sizes are warranted.