Is Neoadjuvant Androgen Deprivation Therapy Necessary for Patients with Intermediate-Risk Prostate Cancer Treated with Proton Therapy?

Presently no prospective, randomized trials have clearly defined the role of neoadjuvant androgen-deprivation therapy (N-ADT) for patients with intermediate-risk (IR) prostate cancer with proton therapy (PT). In this study, we assessed the impact of adding N-ADT to PT on biochemical relapse. Patients with IR prostate cancer (any of the 3 risk factors: PSA 10-20 ng/mL, Gleason Score (GS): 7, T2b-T2c) treated with PT at Hyogo Ion Beam Medical Center from 2001 to 2014 were included in this study. Patients treated with adjuvant ADT or the survivors with follow-up < 24 months were excluded. As a result, a total of 600 patients included this study. By the following methods, whether N-ADT improved biochemical relapse free rate (bRFR) of the IR patients was investigated. 1) Prognostic factor analysis including N-ADT for all IR patients. 2) Subgroup analysis with each risk factors (T classification, GS, PSA and % of positive core) and number or risk factors. The Kaplan-Meier method was used to estimate bRFR. The log-rank test and the Cox proportional hazards model were used for univariate and multivariate analyses, respectively. The median follow-up was 74 months (range, 4 - 135 months). All patients received a total dose of 74 Gy (RBE) in 37 fractions. Of these, 262 (43.7%) patients received N-ADT with the median duration of 7 months (range, 1 - 84 months). For all IR patients, 5- and 10- year bRFR were 90.8% and 82.4%, respectively. N-ADT did not improve bRFR (90.7% vs. 90.8%, P = 0.925) for all IR patients. Age, T classification and PSA were significant prognostic factors on bRFR by multivariate analysis. On the subgroup analysis using each risk factors and number of risk factors, N-ADT did not improve bRFR with statistically significant differences. PT provided excellent biochemical control for patients with IR prostate cancer. In this study, N-ADT did not improve bRFR of patients with IR prostate cancer.