Abstract A138: Impact of racial disparities in follow-up colonoscopy for abnormal stool-screening test results on colorectal cancer incidence and mortality: A simulation modeling analysis
Authors: Alagoz Oguz , Fendrick A. Mark , Vahdat Vahab , Estes Chris , Ozbay A. Burak , Ellis Travelle , Limburg Paul J. , Brooks Durado 
Published: December 2023

Introduction: The benefits of colorectal cancer (CRC) screening programs for average-risk adults rely on completion of follow-up colonoscopy (FU-Col) after a positive result from either the stool-based fecal immunochemical test (FIT) or multi-target stool DNA (mt-sDNA) test. Existing data demonstrate significantly lower rates of FU-Col for Black Americans than White Americans.  However, the contribution of differential FU-Col rates on disparate CRC outcomes among Black and White Americans has not been rigorously evaluated. Methods: We used the CRC-Adenoma Incidence and Mortality (CRC-AIM) model as our analysis platform, with inputs from published literature that report Black adults are approximately 15% less likely to complete FU-Col compared to White adults. CRC-AIM was validated against United Kingdom Flexible Sigmoidoscopy Screening Trial and three National Cancer Institute’s Cancer Intervention and Surveillance Modeling Network (CISNET) CRC models.  We simulated screening with annual FIT and triennial mt-sDNA between ages 45 and 75 versus no screening. We considered two scenarios that assumed perfect adherence to FIT/mt-sDNA screening: 1) FU-Col rates for Black adults are 15% lower than those for White adults; 2) Black adults have the same FU-Col rates as White adults. In a secondary analysis, we considered real-world adherence to FIT (43%) and mt-sDNA (66%) and reran these two scenarios. Lifetime outcomes per 1,000 individuals were reported. Results: Assuming perfect adherence to FIT/mt-sDNA screening and 15% lower FU-Col rates, estimated life-year gains (LYG) from annual FIT and triennial mt-sDNA screening strategies compared to no screening was 227 and 239 per 1,000 individuals, respectively.  If Black adults had the same FU-Col rates as White adults, the LYG would increase to 243 and 256 for FIT and mt-sDNA screening, respectively, which corresponds to a 7% improvement in LYG. Furthermore, elimination of racial disparities in FU-Col rates would reduce CRC incidence by 8% and 9% for FIT and mt-sDNA screening, respectively and reduce CRC mortality by 10% for both FIT and mt-sDNA screening.  Secondary analysis shows that eliminating disparities in FU-Col would lead to 9-11% improvement in LYGs, 5-9% improvement in CRC incidence, and 7-11% improvement in CRC mortality for Black adults considering the real-world adherence to FIT/mt-sDNA screening. Conclusions: Data from this novel simulation modeling study that accounts for differences in FU-Col rates between Black and White Americans suggest that focused efforts to eliminate this gap would improve the anticipated LYG, CRC incidence, and CRC mortality benefits associated with stool-based CRC screening by over 7%, 8%, and 10%, respectively.  Further investigation of this under-appreciated contributor to established racial disparities in CRC control may lead to innovative solutions for improving health equity.  

Citation Format: Oguz Alagoz, A. Mark Fendrick, Vahab Vahdat, Chris Estes, A. Burak Ozbay, Travelle Ellis, Paul J. Limburg, Durado Brooks. Impact of racial disparities in follow-up colonoscopy for abnormal stool-screening test results on colorectal cancer incidence and mortality: A simulation modeling analysis [abstract]. In: Proceedings of the 16th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2023 Sep 29-Oct 2;Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(12 Suppl):Abstract nr A138.