Ethnic Access to and Usage of Microsatellite Instability/Mismatch Repair Testing on Colon Cancers at a Regional Veteran Affairs Medical Center

Abstract Introduction/Objective It has been a National Comprehensive Cancer Network (NCCN) recommendation since 2015 that all colon carcinoma cases should receive mismatch repair and microsatellite instability (MSI/MMR) testing. However, literature on MSI/MMR testing compliance with this recommendation particularly for ethnic minorities and veterans, are sparse in the literature. Methods/Case Report A retrospective review of all invasive colon carcinoma cases from colon or rectum specimens was performed from 2017 to March 8th, 2024, at a regional Veteran Affairs Medical Center (VAMC) as part quality assurance (QA) to collect test performance and demographic information. There had been clinical team/pathologist regular education about the NCCN guidelines. Results (if a Case Study enter NA) There were 210 cases from which 183 out of 219 cases (84%) included MSI/MMR testing. From the total population of 210, 92 (43.8%) were African American, 107 were Caucasian American (51.0%) and others were 11 (5.2%). Among the 183 with MSI/MMR testing, 79 (43.2%) were African American, 94 were Caucasian American (51.4%), with the remainder being 10 (5.5%). Testing rate for MSI/MMR over the years increased from 2021 onwards: 40 out of 43 cases in 2017 (93%), 22 out of 27 in 2018 (81%), 27 out of 33 in 2019 (81%), 24 out of 27 in 2020 (88%), 25 out of 34 in 2021 (74%), 21 out of 21 out of in 2022 (100%), and 24 out of 25 in 2023 to 2024 (96% with 1 patient expiring before testing could be sent). Conclusion From 2022 onwards, all patients received MSI/MMR testing if not expired, which is a substantial improvement demonstrating the impact of education and awareness of the current NCCN guidelines along with its impact on patient management. Furthermore, the VAMC provided equal access to MSI/MMR testing to all ethnic groups, thus serving as a paradigm for health equity for colon cancer testing.