Original Article| Volume 154, P29-35, January 2021

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Single-fraction HDR brachytherapy as monotherapy in low and intermediate risk prostate cancer: Outcomes from two clinical trials with and without an MRI-guided boost

Published:September 09, 2020DOI:


      • Single fraction high dose-rate brachytherapy has high local recurrence rate.
      • Dose escalation with an MR-guided boost to the dominant lesion does not improve outcome.
      • Single fraction protocols should not be used.



      Single-fraction HDR monotherapy for the treatment of localized prostate cancer is appealing, but published outcomes are discouraging. An approach to improve local control is MRI-guided focal dose-escalation to the dominant intraprostatic lesion (DIL). Here we report a comparison of outcomes from two phase II clinical trials with and without a focal boost.


      Patients had low or intermediate-risk disease. Patients in Trial1 received a single 19 Gy HDR implant to the whole prostate. Trial2 incorporated an additional MRI-guided focal DIL boost to at least 23 Gy. ADT was not allowed. Toxicities (CTCAEv4.0) and quality of life (EPIC) were collected. Biochemical failure (BF) was defined as nadir +2. Univariate and multivariate logistic regression analysis was conducted to search for predictors of BF.


      Trial1 had 87 patients with a median follow-up of 62 months, while Trial2 had 60 patients with a median follow-up of 50 months. The five-year cumulative BF rate was 32.6% and 31.3%, respectively (p = 0.9). 77.5% of failures were biopsy-confirmed local failures, all of which underwent local salvage therapy. The addition of a DIL boost was not associated with worse toxicity or QOL. Baseline PSA and Gleason score correlated with BF, but none of the dosimetric parameters was a significant predictor of BF.


      MRI-guided focal boost was safe and well tolerated, but did not improve local control after 19 Gy single-fraction HDR monotherapy, and the control rates were unacceptable. Single-fraction HDR monotherapy for prostate cancer should not be offered outside of clinical trials.


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