The persistence of racial disparities in prostate cancer survival: A time-varying conditional survival and mortality analysis

Background: Racial disparities in prostate cancer survival are well-documented, but it is less clear how these mortality risks evolve as patients survive longer. Conditional survival (CS) provides a more dynamic and accurate prognosis for survivors by updating survival estimates over time. Objective: To investigate racial differences in cancer-specific survival (CSS) and 5-year conditional survival (CS) among men with prostate cancer. We also assessed how the multivariable-adjusted hazard of cancer-specific mortality (CSM) by race changes conditional on time already survived. Methods: We conducted a retrospective cohort study of 235,972 men diagnosed with prostate cancer (2004-2015) from the SEER database, limited to patients with known PSA and Gleason scores. We used Kaplan-Meier methods to estimate 5-year CSS at diagnosis and 5-year CS for men who had already survived 1-5 years. A series of time-varying multivariable Cox proportional hazards models were fit to calculate Hazard Ratios (HRs) for CSM, adjusting for age, sociodemographics, tumor characteristics (stage, grade, PSA, Gleason), and treatment. Results: At diagnosis (0 years survived), 5-year CSS was 95.9% for White men, 96.2% for Asian/Pacific Islander (API) men, 94.6% for Black men, and 92.8% for American Indian/Alaska Native (AI/AN) men. While 5-year CS improved for all groups who survived 5 years, the gap between Black (95.5%) and White (96.1%) men narrowed but persisted. In multivariable Cox models at diagnosis, Black men had a significantly higher hazard of CSM compared to White men (HR: 1.07; 95% CI: 1.03-1.11, P < 0.001). This elevated mortality risk did not attenuate over time. Conversely, API men had a persistent survival advantage (HR at Year 0: 0.72; 95% CI: 0.68-0.77, P < 0.001). The mortality hazard for AI/AN men was not statistically different from White men (HR at Year 0: 1.06; 95% CI: 0.87-1.29, P=0.54). Conclusion: Racial disparities in prostate cancer survival are established at diagnosis and, for Black and API men, persist for at least 5 years, even after adjusting for a comprehensive set of clinical and sociodemographic factors. The persistently higher mortality hazard for Black men highlights that survival gaps are not limited to factors at diagnosis. The lack of a significant difference for AI/AN men, despite lower initial CSS, warrants further investigation. These findings are critical for providing a more accurate, dynamic prognosis in long-term patient counseling.