Highlights
- •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.
Abstract
Purpose
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.
Methods
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.
Results
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.
Conclusions
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.
Keywords
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Article info
Publication history
Published online: September 09, 2020
Accepted:
September 1,
2020
Received in revised form:
August 31,
2020
Received:
August 19,
2020
Identification
Copyright
© 2020 Elsevier B.V. All rights reserved.
