This is a phase I trial with the primary objective of identifying the most compressed dose schedule (DS) tolerable using risk-volume-adapted, hypofractionated, post-operative radiotherapy (PORT) for biochemically recurrent prostate cancer.
Secondary endpoints included biochemical progression free survival (bPFS) and quality of life (QOL).
Patients were treated with one of 3 isoeffective dose schedules (DS1: 20 fractions, DS2: 15 fractions, DS3: 10 fractions) that escalated dose to the imaging-defined local recurrence (73Gy3 EQD2) and de-escalated dose to the remainder of the prostate bed (48Gy3 EQD2). Escalation followed a standard 3+3 design with a 6-patient expansion at the maximally tolerated hypofractionated dose schedule (MTHDS). Dose limiting toxicity (DLT) was defined as CTCAE v.4.0 grade (G) 3 toxicity lasting >4 days within 21 days of PORT completion or grade 4 gastrointestinal (GI) or genitourinary (GU) toxicities thereafter. QOL was assessed longitudinally through 24 months with the EPIC-26.
Between 01/2018 and 12/2023, 15 patients were treated (3 with DS1, 3 with DS2, and 9 with DS3). The median follow-up was 48 months. No DLTs were observed on any DS, and, thus, expansion occurred at DS3. The cumulative incidence of G3 GI and GU toxicity was 7% and 9% at 24 months, respectively, with no G4 events observed. Transient, acute G2+ GI toxicity was most common. QOL worsened transiently during study follow-up in urinary incontinence, GI, and sexual subdomains but was similar to baseline by 24 months. The bPFS was 91% at both 24- and 60-months.
The maximally tolerated hypofractionated dose schedule for hypofractionated, risk-volume-adapted PORT was determined to be DS3 (36.4Gy to the prostate bed and 47.1Gy to the imaging-defined recurrence in 10 daily fractions). No >G3 events were observed. Transient declines in QOL did not persist through 24 months.
International journal of radiation oncology, biology, physics. 2024 Oct 07 [Epub ahead of print]
Krishnan R Patel, Esther Mena, Lindsay S Rowe, Holly Ning, Jason Cheng, Kilian Salerno, Erica Schott, Debbie-Ann Nathan, Erich P Huang, Liza Lindenberg, Peter Choyke, Baris Turkbey, Deborah E Citrin
Radiation Oncology Branch, National Cancer Institute, NIH, Bethesda, MD. Electronic address: ., Molecular Imaging Branch, National Cancer Institute, NIH, Bethesda, MD., Department of Oncology, University of Alberta, Alberta, Canada., Radiation Oncology Branch, National Cancer Institute, NIH, Bethesda, MD., Biometric Research Program, National Cancer Institute, NIH, Rockville, MD. Electronic address: ., Radiation Oncology Branch, National Cancer Institute, NIH, Bethesda, MD. Electronic address: .