Focal MRI-Guided Salvage High-Dose-Rate Brachytherapy in Patients With Radiorecurrent Prostate Cancer

Abstract

Introduction:Whole-gland salvage treatment of radiorecurrent prostate cancer has a high rate of severe toxicity. The standard of care in case of a biochemical recurrence is androgen deprivation treatment, which is associated with morbidity and negative effects on quality of life. A salvage treatment with acceptable toxicity might postpone the start of androgen deprivation treatment, might have a positive influence on the patients’ quality of life, and might even be curative. Here, toxicity and biochemical outcome are described after magnetic resonance imaging–guided focal salvage high-dose-rate brachytherapy in patients with radiorecurrent prostate cancer.Materials and Methods:Seventeen patients with pathologically proven locally recurrent prostate cancer were treated with focal high-dose-rate brachytherapy in a single 19-Gy fraction using magnetic resonance imaging for treatment guidance. Primary radiotherapy consisted of external beam radiotherapy or low-dose-rate brachytherapy. Tumors were delineated with Ga-68–prostate-specific membrane antigen or F18-choline positron emission tomography in combination with multiparametric magnetic resonance imaging. All patients had a prostate-specific antigen level of less than 10 ng/mL at the time of recurrence and a prostate-specific antigen doubling time of ≥12 months. Toxicity was measured by using the Common Terminology Criteria for Adverse Events version 4.Results:Eight of 17 patients had follow-up interval of at least 1 year. At a median follow-up interval of 10 months (range 3-40 months), 1 patient experienced a biochemical recurrence according to the Phoenix criteria, and prostate-specific membrane antigen testing revealed that this was due to a distant nodal metastasis. One patient had a grade 3 urethral stricture at 2 years after treatment.Conclusion:Focal salvage high-dose-rate brachytherapy in patients with radiorecurrent prostate cancer showed grade 3 toxicity in 1 of 17 patients and a distant nodal metastasis in another patient. Whether this treatment option leads to cure in a subset of patients or whether it can successfully postpone androgen deprivation treatment needs further investigation.

Efficacy and toxicity outcomes for patients treated with focal salvage high dose rate brachytherapy for locally recurrent prostate cancer

“…While our study is retrospective and did not include patient reported outcome measures (PROMs) and therefore is at risk of underrepresenting actual levels of toxicity, we only had one patient (2%) with a grade 3 GU toxicity. Our toxicity rates are similar to previous studies of focal salvage HDR and LDR brachytherapy [8][9][10][13][14][15]. As a comparison, the rates of grade 3 GU and GI toxicities reported in previous studies of whole gland salvage brachytherapy are as high as 47% and 20% respectively .…”

“…Our 3 year estimate for bPFS of 41.8% is lower than the study by Murgic et al (61%), although that study only evaluated 15 patients and our cohort included a greater proportion of patients with high risk characteristics which could potentially explain the lower result seen in our study [10]. Other studies of focal salvage HDR brachytherapy either included only small numbers or had limited follow up [9,15]. Few studies of focal salvage LDR brachytherapy exist but this could be a promising technique with 3 year estimates for bPFS reported between 60 and 71% [13,14].…”

“…In our study, where the use of and duration of ADT was at clinician discretion, 74% of patients received ADT and this was for 6 months in most cases. ADT was used in many previous studies of whole gland salvage brachytherapy but it was not used in several studies of focal salvage HDR and LDR brachytherapy [7,10,13,14,39,40]. The rationale for this approach could be that salvage brachytherapy might avoid/delay the need to commence ADT and its associated toxicities and impact on quality of life [10].…”

“…Given the concerns regarding the toxicity of whole-gland salvage therapies, it has been suggested that focal salvage therapy using brachytherapy could be an effective but better tolerated alternative and some prospective early phase studies of focal salvage HDR brachytherapy have been reported [8][9][10]. Advancements in multiparametric magnetic resonance imaging (mp-MRI), positron emission tomography combined with computed tomography (PET-CT) and template-guided biopsies help to localise of the specific area of disease within the prostate to permit precise delivery of focal treatments [11,12].…”

“…Advancements in multiparametric magnetic resonance imaging (mp-MRI), positron emission tomography combined with computed tomography (PET-CT) and template-guided biopsies help to localise of the specific area of disease within the prostate to permit precise delivery of focal treatments [11,12]. At this stage however, there remains limited clinical data and an absence of high quality evidence to support the use of focal salvage brachytherapy [8][9][10][13][14][15].…”