External Beam Radiotherapy With or Without Brachytherapy Boost in Men with Very High-Risk Prostate Cancer: A Large Multicenter International Consortium Analysis.
International journal of radiation oncology, biology, physics
PURPOSE: Very high-risk (VHR) prostate cancer (PC) is an aggressive subgroup with high risk of distant disease progression, and systemic treatment intensification with abiraterone or docetaxel reduces PC-specific mortality (PCSM) and distant metastasis (DM) in men receiving external beam radiotherapy (EBRT) with androgen deprivation therapy (ADT). Whether prostate-directed treatment intensification with addition of brachytherapy (BT) boost to EBRT with ADT improves outcomes in this group is unclear.
METHODS AND MATERIALS: This cohort study from 16 centers across four countries included men with VHR PC treated with (i) dose-escalated EBRT with ≥ 24 months of ADT or (ii) EBRT+BT boost with ≥ 12 months of ADT. VHR was defined by National Comprehensive Cancer Network (NCCN) criteria (clinical T3b-4, primary Gleason pattern 5, or ≥ 2 NCCN high-risk features), and results were corroborated in a subgroup of men who met STAMPEDE trials inclusion criteria (≥ 2 of following: clinical T3-4, Gleason 8-10, or PSA ≥ 40 ng/mL). PCSM and DM between EBRT and EBRT+BT were compared using inverse probability of treatment weight-adjusted Fine-Gray competing risk regression.
RESULTS: Amongst the entire cohort, 270 underwent EBRT and 101 EBRT+BT. After a median follow-up of 7.8 years, 6.7% and 5.9% of men died of PC and 16.3% and 9.9% had DM after EBRT and EBRT+BT, respectively. There was no significant difference in PCSM (sHR, 1.47 [95% CI, 0.57-3.75]; P=.42) or DM (sHR, 0.72, [95% CI, 0.30-1.71]; P=.45) between EBRT+BT and EBRT. Results were similar within the STAMPEDE-defined VHR subgroup (PCSM: sHR, 1.67 [95% CI, 0.48-5.81]; P=.42; DM: sHR, 0.56 [95% CI, 0.15-2.04]; P=.38).
CONCLUSIONS: In this VHR PC cohort, no difference in clinically meaningful outcomes was observed between EBRT alone with ≥ 24 months of ADT compared with EBRT+BT with ≥12 months of ADT. Comparative analyses in men treated with intensified systemic therapy are warranted.
Online ahead of print.
Patel SA, Ma TM, Wong JK, Stish BJ, Dess RT, Pilar A, et al, [Krauss DJ] External beam radiotherapy with or without brachytherapy boost in men with very high-risk prostate cancer: a large multicenter international consortium analysis. Int J Radiat Oncol Biol Phys. 2022 Sep 27:S0360-3016(22)03399-5. doi: 10.1016/j.ijrobp.2022.09.075. Epub ahead of print. PMID: 36179990.