Factors associated with gene mutation testing in United States veterans with metastatic castration-resistant prostate cancer.

Abstract

47 Background: Practice guidelines have been modified to recommend hereditary and tumor gene mutation testing in patients with metastatic castration-resistant prostate cancer (mCRPC) to identify patients for molecularly targeted therapies. Identifying appropriate candidates for testing can be challenging in electronic health records and claims data. In this study, we used natural language processing (NLP) algorithms to identify veterans with mCRPC, reported gene mutation testing rates and identified factors associated with testing. Methods: This is a retrospective observational cohort study using NLP to identify veterans diagnosed with mCRPC between 2016 and 2020. Patient and facility characteristics were reported descriptively. Chi-square and t-tests were used to determine whether differences were statistically significant at a significance level of 0.05 based on receipt of testing. Generalized linear mixed models with binomial error distributions and logit links accounting for clustering by facility were used to determine which factors were independently associated with testing. Results: 9,282 veterans were diagnosed with mCRPC between 2016 and 2020, as determined by NLP algorithms identifying diagnosis of metastatic disease and castration-resistant disease. Among these patients, 381 died within 45 days of their diagnosis, and were excluded from analysis. In the analytic cohort of 8,901 veterans, 1,282 (14%) patients received testing. Of these, 1,041 (81%) received tumor tissue testing and 292 (23%) received hereditary testing. In bivariate analyses, age, race, ethnicity, Commission on Cancer (COC) facility certification, and facility complexity rating differed between veterans who received the test versus who did not (mean age of 73 versus 77, p < 0.0001; 30% versus 24% Black, p < 0.0001; 93% versus 92% non-Hispanic, p = 0.04; 64% versus 63% COC-certified facility, p = 0.04; and 59% versus 52% most complex facility, p < 0.0001). In multivariate analyses, older age and lower facility complexity rating were associated with lower odds of testing (for every 10-year increase in age, adjusted odds ratio [aOR], 95% confidence interval [CI]: 0.54, 0.50-0.58; Mid-high and low complexity facilities compared to highest complexity facilities: aOR, 95% CI: 0.52, 0.32-0.85 and 0.39, 0.22-0.71, respectively). Conclusions: Gene mutation testing in veterans with mCRPC is underutilized. Older age and being seen in a lower complexity facility are independently associated with a lower odds of testing. Patient and facility barriers to testing should be identified to improve guideline concordant care.