Focal boost to dominant intraprostatic lesion (DIL) is an approach for dose-escalation in prostate radiotherapy. In this study, we aim to report the outcomes of two-fraction stereotactic ablative radiotherapy (SABR)+/-DIL boost.
We included sixty patients with low to intermediate risk prostate cancer enrolled in two phase 2 trials (30 patients in each trial). In XXXX1 trial (NCTXXXXXXXX), 26Gy (EQD2 105.4Gy) was delivered to the prostate. In XXXX2 trial (NCTXXXXXXXX), 26Gy was delivered to the prostate, with up to 32Gy boost to MRI-defined DIL (EQD2 156.4Gy). The reported outcomes included PSA response (i.e., <0.4ng/mL) at 4 years (4yrPSARR), biochemical failure (BF), acute and late toxicities, and quality of life (QOL).
In XXXX2, median DIL D99% of 32.3Gy was delivered. Median follow-up was 72.7 months (range: 69.1-75.) in XXXX1 and 43.6 months (range: 38.7-49.5) in XXXX2. The 4yrPSARR was 57% (17/30) in XXXX1 and 63% (15/24) in XXXX2 (P=0.7). The 4-year cumulative BF was 0% in XXXX1 and 8.3% in XXXX2 (P=0.1). The 6-year BF in XXXX1 was 3.5%. For genitourinary toxicities, there were differences in grade ≥1 urinary urgency in the acute (0% vs 47%; P<0.001) and late settings (10% vs 67%; P<0.001) favouring XXXX1. For urinary QOL, no difference was observed in the acute setting, but lower proportion in XXXX1 had minimal clinically important changes in urinary QOL score in the late setting (21% vs 50%; P=0.03). There were no significant differences in gastrointestinal and sexual toxicities and QOL in both acute and late settings between the two trials.
This is the first prospective data comparing two-fraction prostate SABR+/-DIL boost. The addition of DIL boost resulted in similar medium-term efficacy (in 4yrPSARR and BF), with impact on late urinary QOL outcomes.
International journal of radiation oncology, biology, physics. 2023 Jul 05 [Epub ahead of print]
Wee Loon Ong, Patrick Cheung, Hans Chung, William Chu, Jay Detsky, Stanley Liu, Gerard Morton, Ewa Szumacher, Chia-Lin Tseng, Danny Vesprini, Melanie Davidson, Ananth Ravi, Merrylee McGuffin, Liying Zhang, Alexandre Mamedov, Andrea Deabreu, Meghan Kulasingham-Poon, Andrew Loblaw
Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Canada; Department of Radiation Oncology, University of Toronto, Canada; Alfred Health Radiation Oncology, Monash University, Melbourne, Australia., Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Canada; Department of Radiation Oncology, University of Toronto, Canada., Department of Radiation Oncology, University of Toronto, Canada; Molli Surgical., Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Canada., Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Canada; Department of Radiation Oncology, University of Toronto, Canada; Department of Health Policy, Measurement and Evaluation, University of Toronto, Canada. Electronic address: .