Significant interaction between testosterone recovery (TR) and biochemical progression-free survival (BPFS) in intermediate- and high-risk patients with prostate cancer treated with radiation therapy (RT) and androgen deprivation therapy (ADT).

Abstract

202 Background: To examine the interaction testosterone-recovery-free survival (TRFS) and BPFS in patients with intermediate and high-risk prostate cancer treated with combined external beam radiation therapy (EBRT), prostate implant (PI), and ADT. Methods: We prospectively collected data between 1998 and 2010 from 1,564 patients with clinically localized prostate cancer treated by a single physician (DS). 294 patients with NCCN intermediate or high-risk prostate cancer were treated with EBRT, PI, and ADT. 60% of these patients had intermediate-risk disease. Initial prostate-specifc antigen (PSA), Gleason Score (GS), AJCC tumor stage (TStage), and RT parameters were recorded. PSA, and testosterone (T) were measured at each follow-up visit. BPFS was scored using the Phoenix definition. Testosterone recovery occurred when the serum T level rose above 150ng/ml. TR was dichotomized at 2 years. Survival was evaluated using Cox-regression analysis. Results: Median age was 66 yrs-old, intraquartile range (IQR) was 60-71. Median ADT duration (ADTD) was 1.31 years (IQR 0.25-2.35). Testosterone recovery (TR) was seen in 73% of patients. Median TRFS was 3.1 years (IQR 1.94-4.12). Median BPFS was 4.96 years (IQR 3.39-9.12). Overall BPFS was 90% in this patient population. Three patients experienced metastatic failure. There were no prostate cancer deaths. On univariate analysis ADTD (p=0.05), TRFS (p=0.04), GS (p=0.02), and PSA (p=0.05) were significantly associated with BPFS. On multivariable analysis TRFS (p=0.009), TStage (p=0.02), GS (p=0.02), and PSA (p=0.04) were significantly associated with BPFS. Conclusions: Prolonged testosterone suppression after combination EBRT/PI/ADT is strongly associated with improved BPFS. The physiological implications of this finding warrant further study. No significant financial relationships to disclose.