%0 Journal Article
%T DNA mismatch repair and microsatellite instability in colorectal tumors: an observational study in the Veterans Affairs Health Care System.
%A Waller J
%A Gu L
%A De Hoedt AM
%A Freedland SJ
%A Wang T
%A Amonkar M
%A Aurora-Garg D
%A Liaw KL
%A Wehn A
%A Klaassen Z
%J Future Oncol
%V 18
%N 6
%D Feb 2022
%M 35068195
%F 3.674
%R 10.2217/fon-2021-0874
%X Background: Challenges in identifying microsatellite instability (MSI)/mismatch repair (MMR)-tested colorectal carcinoma (CRC) patients in electronic health records have led to gaps in the understanding of MSI-high/deficient mismatch repair prevalence. Methods: An algorithm to identify MSI-/MMR-tested Veterans Affairs patients was developed and an observational study of adult CRC patients with MSI/MMR testing from 2010 to 2018 was undertaken. Results: An optimized model to identify MSI-/MMR-tested patients yielded high positive predictive value (89.0%) and specificity (97.8%). The authors observed MSI-high/deficient mismatch repair CRC in 54 of 291 patients (18.6%); highest frequencies were observed in stages II (25.9%) and III (22.6%) and lowest in stage IV (5.8%). Conclusions: In this real-world study, the authors proposed a novel method of identifying MSI-/MMR-tested patients. Further validation and refinement of this model, and study in a larger CRC cohort, is warranted.