Geographic Variability in Germline Genetic Testing for Prostate Cancer: A Nationwide Medicare Claims Study With Evidence of Low Uptake.

BACKGROUND

Germline genetic testing is recommended for patients with prostate cancer, both localized and advanced, based on disease and family history criteria, with results that may inform targeted therapy. However, real-world utilization of germline genetic testing and potential disparities in access remain inadequately characterized. We analyzed germline genetic testing utilization in a national cohort of Medicare beneficiaries with prostate cancer, examining geographic variation and factors associated with testing.

METHODS

Using nationwide Medicare claims (2019-2023), we identified patients with newly diagnosed prostate cancer and germline genetic testing claims. Patient-level geographic patterns of testing rates were evaluated using Rural-Urban Continuum Codes (metropolitan, urban, rural) and hospital referral regions. Using multivariable logistic regression, we assessed associations between residence type and germline genetic testing receipt, adjusted for sociodemographic covariates. The SEER database was used to estimate the proportion of patients meeting clinicopathologic criteria for testing.

RESULTS

Among 749,202 men with prostate cancer, 17,821 (2.38%) underwent germline genetic testing. Based on SEER data, 36.5% of patients would have met clinicopathologic criteria for testing. Across 306 hospital referral regions, testing rates ranged from 0.29% to 14.1%. Urban residents were less likely to undergo germline genetic testing than metropolitan residents (odds ratio [OR], 0.85; 95% CI, 0.75-0.95). Increasing age (≥81 years: OR, 0.54; 95% CI, 0.50-0.58) and Asian ethnicity (OR, 0.69; 95% CI, 0.58-0.82) were associated with a lower odds of germline genetic testing.

CONCLUSIONS

This study reveals substantial underutilization of germline genetic testing among Medicare beneficiaries with prostate cancer. Despite evidence supporting its use and benefits, <3% of patients underwent testing, even though more than one-third met established criteria. These findings underscore the need to improve regional access to testing and increase awareness among patients and physicians, particularly for older and Asian populations.