Outcomes in patients with high-risk prostate cancer treated with definitive versus adjuvant radiation therapy.

Abstract

133 Background: 20% of men with prostate cancer (PCa) are diagnosed with high-risk disease. The optimal therapy for these patients, prostatectomy followed by adjuvant radiation therapy (ART) or definitive radiation with androgen deprivation (DRT), is still unclear. Previous randomized trials failed to accrue; therefore we sought to answer this using an IRB-approved retrospective cohort study. Methods: High-risk PCa was defined using NCCN criteria. Adjuvant radiation was defined as radiotherapy started within 6 months of prostatectomy. Biochemical progression-free survival (BPFS), castrate resistance-free survival (CRFS), distant metastasis-free survival (DMFS), prostate cancer-specific survival (PCSS), and overall survival (OS) were calculated using Kaplan-Meier estimates. Biochemical failure was defined using the AUA definition in the ART group and by the Phoenix definition in the DRT group. Castrate resistance was defined as ≥2 episodes of rising PSA with testosterone <50 ng/ml or rising PSA despite second line anti-androgen. Statistical analysis was performed using log rank and Cox testing. Results: 60 men with high-risk PCa treated between 1992-2011 were included in the ART group and 154 men were included in the DRT group. 58% of men in the ART group received short course of androgen depravation therapy (ADT). Nearly all men received 2 years of ADT in the DRT group. The median follow up for the ART group was 62 months and 55 months for the DRT group. Men in ART group were younger (p<0.0001) and had a lower pre-treatment PSA (p=0.0338). Log rank testing revealed the ART group had worse BPFS (5 year: 57% vs. 71%; p=0.008), but there was no difference in the other endpoints including CRFS (p=0.9693), DMFS (p=0.7345), PCSS (p=0.5481), or OS (p=0.2557). On multivariable analysis ADT use, ADT length, type of treatment, and stage were not predictive of BRFS whereas Gleason score was (p=.0001). Conclusions: This study suggests that for high-risk PCa patients there is no difference between DRT and ART with regards to BPFS, CRFS, DMFS, PCSS, or OS. Therefore, over a short follow-up period, there does not appear to be a difference between these approaches. Prospective trials are required to validate this finding.