Fifteen-year outcomes of external radiation with or without 6 months of neoadjuvant deprivation therapy for intermediate risk prostate cancer.

Abstract

388 Background: Our aim is to retrospectively compare survival outcomes in intermediate-risk prostate cancer (IRPC) treated with external-beam radiation therapy (EBRT) with or without neoadjuvant-deprivation-therapy (NADT). Methods: Retrospective analysis was performed on 566 IRPC treated with EBRT from 2004-2007. NADT was given to 336 patients, while 230 underwent EBRT alone. Median duration of NADT was 6 months. Median dose of radiation was 75.6 Gy to isocenter. Freedom-from-biochemical-failure (FFBF) was defined by the PSA nadir+2.0. Multi-variable analysis and Kaplan-Meier estimates were performed. Results: Median follow-up was 11.5 years in the NADT+EBRT vs 12.0 years in the EBRT alone group, with up to 19.8 years of follow-up. NADT+EBRT had more adverse factors of clinical stage (p=0.02), iPSA (p<0.01), Gleason group (p=0.02), %cores>50% (p<0.01). 15-year FFBF, metastases-free-survival (MFS), prostate-cancer-specific-survival (PCSS), and overall survival (OS) for NADT+EBRT vs EBRT alone was 52% vs 49% (p=0.41), 85% vs 83% (p=0.59), 91% vs 91% (p=0.67), 53% vs 51% (p=0.82). Conclusions: After 15 years of follow-up, IRPC treated with EBRT with or without 6 months of NADT experienced a high PCSS of 91%, despite a very high PSA failure rate of about 49-52% of the patients. It’s unclear if 6 months NADT in addition to EBRT can improve PCSS or overall survival for IRPC, or just merely delay PSA progression.