Radiother Oncol 2020 Mar 05
Prostate high dose-rate brachytherapy as monotherapy for low and intermediate risk prostate cancer: Efficacy results from a randomized phase II clinical trial of one fraction of 19 Gy or two fractions of 13.5 Gy.
Abstract
Background and purpose
High dose-rate (HDR) brachytherapy as monotherapy is a treatment option for localized prostate cancer, but optimal dose and fractionation is unknown. We report efficacy results of a randomized phase II trial of HDR monotherapy delivered as either one or two fractions.
Materials and methods
Eligible patients had low or intermediate risk prostate cancer, prostate volume <60 cc, and no androgen deprivation use. 170 patients were randomized to receive HDR as either a single fraction of 19 Gy or as two fractions of 13.5 Gy one week apart. Median age was 65 years, median PSA was 6.33 ng/ml, and Grade Group 1, 2 and 3 was present in 28%, 60%, and 12%, respectively. There was no difference in baseline factors between arms and 19%, 51% and 30% had low risk, favourable intermediate and unfavourable intermediate risk disease, respectively. The Phoenix definition was used to define biochemical failure, all local failures were confirmed by biopsy and toxicity was assessed using CTCAE v.4.
Results
Median follow-up was 60 months. PSA decreased more quickly in the 2-fraction arm (p = 0.009). Median PSA at 5-years was 0.65 ng/ml in the single fraction and 0.16 ng/ml in the 2-fraction arm. The 5-year biochemical disease-free survival and cumulative incidence of local failure was 73.5% and 29% in the single fraction arm and 95% (p = 0.001) and 3% (p < 0.001) in the 2-fraction arm, respectively. Recurrence was not associated with initial stage, grade group, or risk group. Grade 2 late rectal toxicity occurred in 1% while the incidence of grade 2 and 3 urinary toxicity was 45% and 1%, respectively, with no difference between arms.
Conclusions
HDR monotherapy delivered as two fraction of 13.5 Gy is well tolerated with a high cancer control rate at 5 years. Single fraction monotherapy is inferior and should not be used.
Related Questions
How do you talk to patients with intermediate-risk prostate cancer deciding between LDR brachytherapy (monotherapy) vs HDR mono vs SBRT vs EBRT, in terms of the comparative side effect profile of each approach?
It’s hard to add much to Dr. @Dr. First Last's excellent evidence-based answer, but I’ll elaborate on the counseling aspect from my perspective. Introduction: I start by acknowledging how difficult it is to weigh several totally foreign options and acknowledge the gravity of the decision. My patient...
How do you manage a seminal vesicle recurrence after prostate brachytherapy?
Finding more of these in the PSMA era. Have managed a few patients with SBRT +/- ADT adjusting dose based on overlapping OAR if needed.