IMPACT OF ULTRAHIGH BASELINE PSA LEVELS ON BIOCHEMICAL AND CLINICAL OUTCOMES IN TWO RADIATION THERAPY ONCOLOGY GROUP PROSTATE CLINICAL TRIALS

Purpose To assess ultrahigh (UH; prostate-specific antigen [PSA] levels ≥50 ng/ml) patient outcomes by comparison to other high-risk patient outcomes and to identify outcome predictors. Methods and Materials Prostate cancer patients (PCP) from two Phase III Radiation Therapy Oncology Group clinical trials (studies 9202 and 9413) were divided into two groups: high-risk patients with and without UH baseline PSA levels. Predictive variables included age, Gleason score, clinical T stage, Karnofsky performance score, and treatment arm. Outcomes included overall survival (OS), distant metastasis (DM), and biochemical failure (BF). Unadjusted and adjusted hazard ratios (HRs) were calculated using either the Cox or Fine and Gray's regression model with associated 95% confidence intervals (CI) and p values. Results There were 401 patients in the UH PSA group and 1,792 patients in the non-UH PSA PCP group of a total of 2,193 high-risk PCP. PCP with UH PSA were found to have inferior OS (HR, 1.19; 95% CI, 1.02-1.39, p = 0.02), DM (HR, 1.51; 95% CI, 1.19-1.92; p = 0.0006), and BF (HR, 1.50; 95% CI, 1.29-1.73; p Conclusions UH PSA levels at diagnosis are related to detrimental changes in OS, DM, and BF. All three outcomes can be modeled by various combinations of all predictive variables tested.