ESTRO 2024 - Abstract Book

S418

Brachytherapy - Urology

ESTRO 2024

Conclusion:

Our results shows that UHF is associated with better early GU, GI and SHIM score. Late GU, GI toxicities, BCR, BRFS and OS appears to be similar between UHF and MHF. These results need long follow up and long terms results to be confirm.

Keywords: Prostate, Brachytherapy, Ultra-hypofractionation

References:

[1] Crook JM, Tang C, Thames H, Blanchard P, Sanders J, Ciezki J, et al. A biochemical definition of cure after brachytherapy for prostate cancer. Radiother Oncol 2020;149:64 – 9. https://doi.org/10.1016/j.radonc.2020.04.038.

1931

Mini-Oral

Local relapse patterns after MR-assisted salvage HDR prostate brachytherapy: a prospective study

Hans T Chung 1,2 , John M Hudson 1,2 , Andrew Loblaw 1,2 , Chia-Lin Tseng 1,2 , Moti Paudel 1,2 , Melanie Davidson 1,2 , Matt Wronski 1,2 , Masoom Haider 3 , Andrea Deabreu 1 , Gerard Morton 1,2 1 Sunnybrook Odette Cancer Center, Radiation Oncology, Toronto, Canada. 2 University of Toronto, Radiation Oncology, Toronto, Canada. 3 University of Toronto, Medical Imaging, Toronto, Canada

Purpose/Objective:

Salvage high dose rate (HDR) prostate brachytherapy is an accepted treatment option for intra-prostatic recurrent localized prostate cancer after previous radiation. Recently, our center reported the outcomes of two companion prospective phase 2 studies of MR-assisted salvage HDR prostate brachytherapy: whole-gland with an intra prostatic boost, and focal-gland. Both studies mandated post-salvage multiparametric MRI (mpMRI). This study explores the subsequent relapse pattern and dosimetry of the subset of patients who had relapse/persistent disease on post-salvage mpMRI.

Material/Methods:

Eligible patients had biopsy confirmed localized prostate cancer who relapsed >30 months after primary brachytherapy and/or external radiotherapy with a negative metastatic workup and IPSS <15. Ultrasound (US)- based HDR brachytherapy with cognitive fusion initially then subsequently contour-based deformable registration between the diagnostic mpMRI and ultrasound images was performed. For FG salvage brachytherapy, the prescription dose was 27Gy in 2 fractions, 1-2 weeks apart, to the dominant intra-prostatic lesion (DIL) with a 3-5mm