Whole pelvic irradiation for prostate cancer patients with a biochemical relapse following radical prostatectomy: The era of robot-assisted minimally invasive surgery.

Abstract

210 Background: We hypothesized that the addition of whole pelvic radiotherapy (WPRT) might improve biochemical outcome in salvage radiotherapy (RT) for biochemical failure (BCF), especially in patients with postoperative high-risk features after radical prostatectomy (RP) being good candidates beneficial from WPRT. Methods: From August 2004 to April 2012, 180 patients who experienced BCF after RP were treated with salvage RT. The primary end point was the biochemical relapse-free survival (bRFS) defined as no prostate-specific antigen (PSA) failure and no additional salvage treatments. Patients were stratified into theee groups; prostate bed radiotherapy (PBRT) alone (n = 52), PBRT with hormone (n = 85), and WPRT with hormone (n = 43). The effects of WPRT combined with hormone was measured in the high-risk patients defined as pN1 stage or inadequate pelvic lymph node dissection (harvested lymph nodes number of less than four). Toxicity from treatment was recorded when genitourinary or gastrointestinal (GI) events occurred. Results: The median follow-up was 43 months (8 to 103 months). The independent predictors for poor bRFS were time to PSA failure less than or equal to 1 year, PSA at salvage greater than 1 ng/mL, PSA doubling time less than 6 months, and PBRT alone group. The risk of BCF after salvage RT was significantly higher in PBRT alone group in comparison to that of WPRT with hormone group (hazard ratio [HR], 3.9; 95% CI, 1.8-8.3, p <0.001), but the outcomes of PBRT with hormone was not statistically different from that of WPRT with hormone (p = 0.67). The advantage of WPRT and hormone over PBRT alone was only observed in the high-risk patients (HR, 5.7; 95% CI, 1.8-17.7, p = 0.003), and not in other patients (HR, 3.2; 95% CI, 0.7-14.9. p = 0.14). Patient treated with WPRT had more greater than or equal to grade 2 late GI toxicity than those having PBRT (17% vs. 5%, p= 0.01). Conclusions: Patients with postoperative high risk features could benefit from WPRT and hormone therapy for postoperative BCF. The additional toxicity by WPRT and long-term outcomes warrant further investigations.