Two versus five stereotactic ablative radiotherapy treatments for localized prostate cancer: A quality of life analysis of two prospective clinical trials.

Stereotactic ablative radiotherapy (SABR) is appealing for prostate cancer (PCa) due to low α/β, and increasing the dose per fraction could improve the therapeutic index and lead to a better quality of life (QOL). Here we report the outcomes of a QOL comparison between two phase II clinical trials: two vs. five fraction prostate SABR.

Patients had low or intermediate risk PCa. The doses prescribed were 26 Gy/2 and 40 Gy/5. Expanded prostate cancer index composite was collected. Urinary, bowel and sexual domains were analyzed. Minimal clinically important change (MCIC) was defined as >0.5 standard deviation.

30 and 152 patients were treated with 2-fraction and 5-fraction SABR. Median follow-up was 55 and 62 months. Five-year biochemical failure rate was 3.3% and 4.6%. The 2-fraction cohort had a significantly better mean QOL over time in the bowel domain (p = 0.0004), without a significant difference in the urinary or sexual domains. The 2-fraction cohort had a significantly lower rate of bowel MCIC (17.8% vs 42.3%, p = 0.01), but there was no difference in urinary (24.1% vs 35.7%) or sexual (15.3% vs 29.2%) MCIC. For MCIC x2 (moderate QOL change), the 2-fraction trial had significantly lower MCIC rates in both the bowel (7.1% vs 24%, p = 0.04) and sexual (0 vs 17.6%, p = 0.01) domains.

2-Fraction SABR is feasible to deliver and well tolerated, with significant signals of improved bowel and sexual QOL. A randomized trial of two vs. five fractions for prostate SABR is needed to confirm the promising findings of this study.

Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology. 2019 Jun 29 [Epub ahead of print]

Yasir Alayed, Harvey Quon, Patrick Cheung, William Chu, Hans T Chung, Danny Vesprini, Aldrich Ong, Amit Chowdhury, Dilip Panjwani, Joelle Helou, Geordi Pang, Renee Korol, Melanie Davidson, Ananth Ravi, Boyd McCurdy, Liying Zhang, Alexandre Mamedov, Andrea Deabreu, Angela Commisso, Kristina Commisso, Andrew Loblaw

Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Canada; Department of Radiation Oncology, University of Toronto, Canada; Division of Radiation Oncology, College of Medicine, King Saud University, Riyadh, Saudi Arabia., Department of Radiation Oncology, Tom Baker Cancer Centre, Calgary, Canada., Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Canada; Department of Radiation Oncology, University of Toronto, Canada., CancerCare Manitoba, Winnipeg, Canada., Compassionate Cancer Centers, India., Department of Radiation Oncology, University of Toronto, Princess Margaret Cancer Centre, Canada., Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Canada., University Health Network, Toronto, Canada., Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Canada; Department of Radiation Oncology, University of Toronto, Canada. Electronic address: .