Purpose: Little is known about the uptake of germline genetic testing for patients with prostate cancer after 2018 guideline changes. This study characterizes genetic service referral patterns and predictors of referrals among patients with prostate cancer.
Methods: A retrospective cohort study using electronic health record data was conducted at an urban safety-net hospital. Individuals diagnosed with prostate cancer between January 2011 and March 2020 were eligible. The primary outcome was referral to genetic services after diagnosis. Using multivariable logistic regression, we identified patient characteristics associated with referrals. Interrupted time series analysis using a segmented Poisson regression examined whether guideline changes resulted in higher rates of referral after implementation.
Results: The cohort included 1,877 patients. Mean age was 65 years; 44% identified as Black, 32% White; and 17% Hispanic or Latino. The predominant insurance type was Medicaid (34%) followed by Medicare or private insurance (25% each). Most were diagnosed with local disease (65%), while 3% had regional and 9% had metastatic disease. Of the 1,877 patients, 163 (9%) had at least one referral to genetics. In multivariable models, higher age was negatively associated with referral (odds ratio [OR], 0.96; 95% CI, 0.94 to 0.98), while having regional (OR, 4.51; 95% CI, 2.44 to 8.34) or metastatic disease (OR, 4.64; 95% CI, 2.98 to 7.24) versus local only disease at diagnosis was significantly associated with referral. The time series analysis demonstrated a 138% rise in referrals 1 year after guideline implementation (relative risk, 3.992; 97.5% CI, 2.20 to 7.24; P < .001).
Conclusion: Referrals to genetic services increased after guideline implementation. The strongest predictor of referral was clinical stage, suggesting opportunities to raise awareness about guideline eligibility for patients with advanced local or regional disease who may benefit from genetic services.