Ten-year outcomes for prostate cancer patients with Gleason 8 through 10 treated with external beam radiation and high-dose-rate brachytherapy boost in the PSA era

Abstract

High-dose-rate (HDR) brachytherapy boost represents a method to dose escalate in high-risk prostate cancer; the purpose of this analysis is to report long-term outcomes for a group of high-risk patients with Gleason 8 through 10 prostate cancer treated with HDR brachytherapy boost from a multi-national cohort study. Between 1987 and 2002, 483 patients with Gleason 8–10 prostate cancer were treated on four prospective trials of HDR boost. Conformal external beam radiotherapy (EBRT) was delivered to the pelvis (dose range 36–50.4 Gy) along with HDR boost for a combined biologic equivalent dose (BED) of 215–366 Gy (α/β = 1.2) and cumulative dose of 64–72 Gy. Mean/median follow-up was 6.1/5.1 years. The 10-year rates of biochemical control (BC), distant metastases (DM), clinical failure (CF), cause-specific survival (CSS), and overall survival (OS) were 53.5, 22.1, 25.6, 82.6, and 62.7 %, respectively. Androgen deprivation was given in 69.9 % of patients (predominantly short course) but did not significantly improve BC, DM, CSS, or OS. When stratified by initial PSA (iPSA), 10-year outcomes were improved with lower iPSA (<40) including BC (57.4 vs. 10.3 %, p < 0.001); freedom from distant metastases (81.5 vs. 43.4 %, p < 0.001); CSS (85.0 vs. 59.1 %, p < 0.001); and OS (63.8 vs. 47.9 %, p = 0.02). A combination of HDR brachytherapy boost and EBRT provides a high BED with high rates of disease control and excellent disease specific survival for patients with Gleason 8 through 10 prostate cancer even with iPSA up to 40 ng/ml. Hormonal therapy did not improve outcomes in this cohort of patients when the radiation dose was escalated with an HDR prostate boost.