Focal low dose-rate brachytherapy for low to intermediate risk prostate cancer: preliminary experience at an Australian institution

Elliot Anderson; Lloyd M L Smyth; Richard O'Sullivan; Andrew Ryan; Nathan Lawrentschuk; Jeremy Grummet; Andrew W See

doi:10.21037/tau-21-508

Focal low dose-rate brachytherapy for low to intermediate risk prostate cancer: preliminary experience at an Australian institution

Transl Androl Urol. 2021 Sep;10(9):3591-3603. doi: 10.21037/tau-21-508.

Authors

Elliot Anderson¹, Lloyd M L Smyth², Richard O'Sullivan^{3

4}, Andrew Ryan⁵, Nathan Lawrentschuk^{6

7

8

9}, Jeremy Grummet^{1

10}, Andrew W See²

Affiliations

¹ Department of Surgery, Central Clinical School, Monash University, Melbourne, Australia.
² Icon Cancer Centre, Richmond, Australia.
³ Healthcare Imaging Services, Richmond, Australia.
⁴ Department of Medicine, Monash University, Melbourne, Australia.
⁵ TissuPath Specialist Pathology Services, Mount Waverley, Australia.
⁶ Division of Cancer Surgery, Peter MacCallum Cancer Centre, Melbourne, Australia.
⁷ Department of Urology, Royal Melbourne Hospital, Melbourne, Australia.
⁸ Department of Surgery, University of Melbourne, Melbourne, Australia.
⁹ EJ Whitten Centre for Prostate Cancer Research, Epworth Healthcare, Melbourne, Australia.
¹⁰ Epworth Healthcare, Richmond, Australia.

Abstract

Background: Focal treatment for prostate cancer (PCa) is a hybrid approach combining ablative treatment of the involved prostate gland and continued active surveillance (AS) of the unaffected gland. Low dose-rate (LDR) brachytherapy can be used as a lesion-targeted focal therapy, however, further studies are required to support its use. The aim of this study is to evaluate the dosimetry, toxicity and oncological outcomes of men receiving lesion-targeted focal LDR brachytherapy for low to intermediate risk PCa.

Methods: This is a retrospective cohort study of 26 men with unifocal, low to intermediate grade PCa diagnosed on a combination of multiparametric-magnetic resonance imaging (mp-MRI) and targeted plus template transperineal (TP) biopsy, who received focal LDR brachytherapy at a single institution. Brachytherapy involved a single monotherapy implant using iodine-125 seeds to deliver a prescribed dose of 145 Gy to the index lesion.

Results: The mean focal planning target volume (F-PTV) as a percentage of the prostate volume was 24.5%. The percentage of the focal gross tumour volume (F-GTV) receiving 100% of the prescription dose was 100% for 12 patients and ≥98% for 18 patients. The median follow-up for toxicity and biochemical control outcomes was 23.1 [interquartile range (IQR) 19.1-31.3] and 24.2 (IQR 17.9-30.0) months, respectively. Grade 2 urinary and erectile toxicities were reported by 29.2% and 45.8% of patients, respectively, with resolution of urinary symptoms to baseline by last follow-up. There were no grade ≥3 urinary or erectile toxicities or grade ≥2 rectal toxicity. All 21 patients who underwent a repeat mp-MRI and TP biopsy at 12-24 months post-treatment were negative for clinically significant disease and 25 (96.2%) patients were free from biochemical failure (FFBF).

Conclusions: Focal LDR brachytherapy is associated with a favourable toxicity profile and a high rate of control of significant PCa at 12-18 months post-treatment. We have commenced the LIBERATE prospective registry in focal LDR brachytherapy based on the highly encouraging outcomes of this initial experience.

Keywords: Brachytherapy; focal therapy; magnetic resonance imaging (MRI); prostate cancer (PCa).