Biochemical and Survival Outcomes in Patients With T3 Prostate Adenocarcinoma Treated With Brachytherapy

Abstract

Purpose/Objective(s): To evaluate the freedom from biochemical failure (FFBF), prostate cancer-specific survival (PCSS), and overall survival (OS) in patients with cT3a-b prostate adenocarcinoma treated at a single institution. Materials/Methods: One hundred seven patients with cT3a-b, N0, M0 prostate adenocarcinoma underwent I-125 (72%) or Pd-103 (28%) low dose rate brachytherapy from 1998-2007. Seventy-five patients (70%) received supplemental external beam radiation therapy as part of combined modality therapy (CMT). Thirty-two patients (30%) underwent implant alone (MT). Ninety-two patients (86%) received androgen deprivation therapy (ADT). Median (range) age, pre-treatment PSA (iPSA), duration of ADT and follow-up were 69 years (47-93), 12.7 ng/ml (1.4-160), 4 months (2-36) and 73 months (9-160), respectively. Fifty-five men (51%) had Gleason sum (GS) 8-10. Eighty-nine patients (86%) had 50% of cores involved. Univariate analysis (UVA) was performed using the logrank test and Cox proportional hazards for continuous variables with the following covariates: age, T-stage (T3a vs. T3b), GS, iPSA, percent positive cores (PPC), ADT use, and implant setting (CMT vs. MT). Multivariable analysis (MVA) was performed using Cox proportional hazards modeling and included T-stage, GS, iPSA and all covariates with p-value <0.1 on UVA. Results: Kaplan-Meier estimates for FFBF, PCSS and OS are described in Table 1. On UVA, only CMT was associated with improved FFBF. CMT, younger age (p Z 0.09), and lower PSA (p<0.01) were associated with improved PCSS. CMT, younger age (p<0.01), higher GS (p Z 0.09), and lower iPSA (p Z 0.04) were associated with improved OS. ADT was not associated with FFBF, PCSS, or OS for the overall cohort or on subgroup analysis. MVA revealed CMTwas associated with improved FFBF (Hazard ratio [HR]: 0.28, 95% Confidence Interval [CI]: 0.14-0.59; p<0.01). Lower iPSA was associated with improved PCSS (HR: 0.98, 95% CI: .96-1.00; p Z 0.01), but CMTwas not (HR: 0.41, 95% CI: 0.1-1.73; pZ 0.23). Lower iPSA was associated with improved OS (HR: 0.98, 95% CI: 0.97-1.00; p<0.01). CMT had a trend towards improved OS (0.44, 95% CI: 0.171.12; p Z 0.09) and higher GS had a trend towards worse OS (HR: 1.35, 95% CI: 0.944-1.93; p<0.1). Conclusions: In patients with cT3a-b prostate adenocarcinoma, CMT is associated with improved biochemical control but may not be associated with PCSS or OS when controlling for other factors. The benefit of ADT in patients treated with brachytherapy is unclear.