ASCO 2017: Ten-year overall and prostate cancer specific mortality in high-risk patients after high-dose-rate brachytherapy combined with external beam radiation therapy (HDR-BT/EBRT) compared with EBRT alone

Chicago, IL (UroToday.com) The effect of dose-escalation with high-dose-rate brachytherapy (HDR-BT) boost for high-risk prostate cancer (PCa) is not known. Dr. Trude Wedde presented a retrospective study aiming to compare 10-year PCa-specific mortality (PCSM) and overall mortality (OM) in non-metastatic patients treated with HDR-BT/external beam radiation therapy (EBRT) during the years 2004-2010 to EBRT alone from a historical randomized controlled trial - SPCG-7, 1996-2003).1 

Overall, 325 patients were included in the HDR-BT group, vs. 296 in the EBRT alone group. HDR-BT boosts (10 Gy x 2) were given 2 weeks apart followed by 50 Gy conformal EBRT (2 Gy x 25) to the prostate and seminal vesicles (assuming alpha/beta ratio of 3, EQD2 = 102 Gy). The HDR-BT/EBRT group received Androgen Deprivation Therapy (ADT) for a total of 2 years. Patients in the control group received 70 Gy (2Gy x 35) to the prostate and seminal vesicles with lifelong Anti-Androgen Treatment (AA). Clinical stage and Gleason score were generally similar. In both groups the median age was 66 years. Median follow-up was 104 (range 13-120) and 120 (range 3-120) months for the HDR-BT/EBRT and EBRT groups respectively. KM plots revealed a 1.8% risk of PCSM in the HDR-BT/EBRT patient group and an 8.4% risk in the EBRT cohort (p = 0.001). For OM, the figures were 12.3% in the HDR-BT/EBRT group compared to 23.3% in the EBRT group (p = 0.014). In the Cox regression analysis, treatment (HR = 3.9, CI95% 1.8-8.3) and Gleason score (HR = 3.2, CI95% 1.8-5.9) were significantly associated with PCSM whilst T-stage, age and PSA levels were not. Treatment (HR = 1.7, CI95% = 1.1-2.6) was the only factor significantly associated with OM. 

In men with high-risk PCa dose-escalation with HDR-BT/EBRT compared to EBRT alone resulted in a significantly decreased risk of 10-year PCSM and OM despite shorter length of hormonal therapy. PCSM was significantly influenced by both Gleason score and type of treatment, whereas treatment remained the only significant covariate for OM.

Presented By: Trude Baastad Wedde, Oslo University Hospital, Oslo, Norway

Written By: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre, Toronto, Ontario, Canada
Twitter: @GoldbergHanan

at the 2017 ASCO Annual Meeting - June 2 - 6, 2017 - Chicago, Illinois, USA

Reference:
1. Widmark A, Klepp O, Solberg A, et al. Endocrine treatment, with or without radiotherapy, in locally advanced prostate cancer (SPCG-7/SFUO-3): an open randomised phase III trial. Lancet (London, England) 2009; 373(9660): 301-8.
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