Effect of Patient Demographic Characteristics and Radiation Timing on PSA Reduction in Patients Treated With Definitive Radiation Therapy for Prostate Cancer

In this study we examined demographic and temporal factors that affect prostate-specific antigen (PSA) dynamics during and after radiation treatment in a cohort of 147 patients who were diagnosed with low- or intermediate-risk prostate cancer. Overall, these factors were not found to be associated with PSA change due to radiation treatment, but did predict PSA level at diagnosis, suggesting that the greatest disparities lie in disease presentation. Introduction: The purpose of this study was to assess how demographic characteristics and temporal factors including time to treatment (TTT) and elapsed time of treatment (ETT) affect prostate-specific antigen (PSA) levels during and after radiation treatment for low- and intermediate-risk prostate cancer. Patients and Methods: A retrospective review of 1584 patients was conducted on patients diagnosed with prostate cancer between 2005 and 2013, from which 147 patients were found to have completed definitive external beam radiation therapy (EBRT) monotherapy. Demographic data, TTT (days between diagnosis and EBRT start date), ETT (days between EBRT start and stop date), and Gleason score were collected on these patients and analysis of variance was performed to analyze the relationship of these factors with PSA changes. PSA changes were calculated during treatment as the difference between pre- and posttreatment PSA levels and after treatment as 3-year and overall PSA velocities. Results: Patients who spoke Haitian Creole (P = .039) and those with a longer ETT (P = .029) had significantly greater PSA decline during treatment, primarily as a result of higher pretreatment PSA levels. Patients with Gleason score 4+3 disease had significantly greater 3-year (P = .033) and overall (P = .019) PSA velocities. Race and/or ethnicity, insurance type, marital status, and age were not associated with any PSA variable. Conclusion: Disparities in prostate cancer are not reflected in PSA dynamics during or after radiation treatment, but are evident in PSA level at presentation. Timeliness of treatment was not found to affect true PSA change due to EBRT in low- and intermediate-risk prostate cancer patients.