Purpose: We examined the survival impact of a course of 6 months or less of adjuvant/concurrent androgen deprivation in patients with unfavorable prostate cancer treated to high radiation doses with external beam (EBRT) and a high dose rate (HDR) brachytherapy boost.
Materials and methods: Between 1986 and 2000, 507 patients were treated with pelvic EBRT (46 Gy) with HDR prostate brachytherapy as a boost. The biological equivalent EBRT dose was between 90 and 130 Gy. At Kiel University and at William Beaumont Hospital 198 and 309 patients were treated. Patient eligibility was pretreatment prostate specific antigen 10 ng/ml or greater, Gleason score 7 or greater, or clinical stage T2b or greater. The brachytherapy dose was escalated from 5.5 x 3 to 15 x 2 Gy. Patients were divided between 177 receiving and 330 not receiving androgen suppression therapy (AST). AST was given for a mean of 6 months. The American Society for Therapeutic Radiology and Oncology biochemical failure definition was used.
Results: Mean patient age was 68 years. Mean followup was 4.8 years (range 0.7 to 15.3), that is 4.5 years for AST and 4.9 for radiation alone. Five-year actuarial rates for biochemical control were 74% and 76%, for overall survival they were 81% and 87%, and for disease-free survival they were 67% and 66%, while cause specific survival with and without AST was 90% and 98%, and the 5-year metastatic rates were 10.7% and 6.9%, respectively. On multivariate analysis AST did not improve biochemical control.
Conclusions: Pelvic EBRT interdigitated with a transrectal ultrasound guided HDR boost is an excellent method of delivering a high radiation dose to the prostate without rendering the patient radioactive. This trial showed high overall, cause specific and no biochemical evidence of disease survival. For this unfavorable group of patients the addition of a course of 6 months or less of neoadjuvant/concurrent AST to a high radiation dose did not appear to confer a 5-year therapeutic advantage. However, it added side effects and the significant cost of hormones.