Abstract PO-247: Is colorectal cancer screening in West Africa worthwhile? A prospective multi-institutional study of 2,330 average-risk Nigerians using fecal immunochemical testing (FIT)

Objective: The estimated incidence of CRC is rising in many African countries. In Nigeria, it is the fourth most common cause of cancer death. More than half of CRC patients in Nigeria present with metastatic disease. Early detection and screening for CRC is a goal of the Nigerian National Cancer Control Plan. This study assessed the performance of the fecal immunochemical test (FIT) as a CRC screening modality in an average-risk population in Nigeria. Methods: A population-based, cross-sectional study of FIT-based CRC screening was undertaken. Asymptomatic average-risk participants aged 45-75 years in three states in Southwest Nigeria were screened using a qualitative (50ng/mL) FIT test. Participants were invited to enroll using age- and sex-stratified convenience sampling following community outreach. Participants with positive test results underwent colonoscopy and the positive predictive value (PPV) of FIT-based CRC screening for CRC and advanced adenomas (tubulovillous, villous or high grade dysplasia) was calculated. Information on demographics, cancer knowledge, and acceptability of the FIT test and colonoscopy were also collected. Results: Between January-April 2021, 2330 participants in 3 states (Osun, Kwara, Lagos) were enrolled in the study. The median age was 57 years. 68% had at least secondary level education. Participants were evenly spread across wealth quintiles. Baseline knowledge of CRC symptoms among participants was low, especially outside of Lagos. The test return rate was 90.6%, and FIT positivity rate was 20.5% overall (n=432); 11.2% in Lagos, 20.4% in Osun, and 27.8% in Kwara states. Among the FIT positive patients who completed colonoscopy (n=285; 66.0%), the positive predictive value (PPV) for invasive adenocarcinoma was 1.1%, and for advanced adenoma was 1.8%.[KTP1] [AD2] The acceptability of fecal-based CRC screening among participants was very high. Conclusions: CRC screening with qualitative FIT testing in Southwest Nigeria is feasible and acceptable to average-risk asymptomatic participants. The high false-positive rates and low PPV for advanced neoplasia, however, suggest it is not an optimal screening tool in this environment, particularly given the health resources required for endoscopic evaluation. Citation Format: Olusegun I. Alatise, Anna J. Dare, Patrick A. Akinyemi, Fatima B. Abdulkareem, Samuel A. Olatoke, Gregg C. Knapp, Peter T. Kingham. Is colorectal cancer screening in West Africa worthwhile? A prospective multi-institutional study of 2,330 average-risk Nigerians using fecal immunochemical testing (FIT) [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-247.