Although radiation dose escalation improves prostate cancer disease control, it can cause increased toxicity. Genitourinary (GU) symptoms after prostate radiotherapy impact patient health related Quality of Life (QoL). We compared patient-reported genitourinary QoL outcomes following two alternative urethral sparing SBRT (US-SBRT) regimens.
EPIC-26 GU scores were compared between two US-SBRT trials. The SPARK trial prescribed a "Monotherapy" dose of 36.25 Gy in 5 fractions to the prostate. The PROMETHEUS trial prescribed two phases; a 19-21 Gy in 2 fraction "Boost" to the prostate, followed by 46 Gy in 23 fractions or 36 Gy in 12 fractions. The Biological Effective Dose (BED) for urethral toxicity was 123.9 Gy for Monotherapy, and 155.8-171.2 Gy for Boost. Mixed effects logistic regression models were utilised to estimate the difference in the odds of a Minimal Clinically Important Change (MCIC) from baseline EPIC-26 GU score between regimens at each follow-up.
46 Monotherapy and 149 Boost patients completed baseline EPIC-26 scoring. Mean EPIC-26 GU scores revealed statistically superior urinary incontinence outcomes for Monotherapy at 12 months (mean difference 6.9 [95% CI 1.6 - 12.1]; p = .01), and 36 months (mean difference 9.6 [95% CI 4.1 - 15.1]; p < .01). Monotherapy also revealed superior mean urinary irritative/obstructive outcomes at 12 months (mean difference 6.9 [95% CI 2.0 - 12.9] p < .01), and 36 months (mean difference 6.3 [95% CI 1.9 - 10.8] p < .01). For both domains, and at all time points, the absolute differences were <10%. There were no significant differences in the odds of reporting a MCIC between regimens at any time-point.
Even in the presence of urethral sparing, the higher BED delivered in the Boost schedule may have a small adverse impact on GU QoL compared with Monotherapy. However, this did not translate to statistically significant differences in Minimal Clinically Important Changes. Whether the higher BED of the boost arm offers an efficacy advantage is being investigated in the TROG 18.01 NINJA randomized trial.
International journal of radiation oncology, biology, physics. 2023 Mar 06 [Epub ahead of print]
Matthew Richardson, Mark Sidhom, Paul Keall, Lucy Leigh, Helen Ball, Joseph Bucci, Sarah Gallagher, Peter Greer, Amy J Hayden, Andrew Kneebone, David Pryor, Shankar Siva, Jarad Martin
Department of Radiation Oncology, Calvary Mater Newcastle, Waratah, NSW, Australia. Electronic address: ., Department of Radiation Oncology, Liverpool Cancer Therapy Centre, Liverpool, NSW, Australia; Faculty of Medicine, Southwest Sydney Clinical School, University of New South Wales, NSW, Australia., ACRF Image X Institute, The University of Sydney, NSW, Australia., Hunter Medical Research Institute, Lot 1 Kookaburra Circuit, New Lambton Heights, NSW, Australia., St George Hospital, Cancer Care Centre, Sydney, NSW, Australia; University of New South Wales, Sydney, NSW, Australia., Department of Radiation Oncology, Calvary Mater Newcastle, Waratah, NSW, Australia., Department of Radiation Oncology, Calvary Mater Newcastle, Waratah, NSW, Australia; School of Mathematical and Physical Science, University of Newcastle, Callaghan, NSW, Australia., Department of Radiation Oncology, Westmead Hospital, Sydney, NSW, Australia; School of Medicine, Western Sydney University, Sydney, Australia., Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia; Department of Radiation Oncology, Royal North Shore Hospital, Sydney, NSW, Australia., Department of Radiation Oncology Princess Alexandra Hospital, Brisbane, QLD, Australia; Queensland University of Technology, Brisbane, QLD, Australia., Sir Peter MacCallum Department of Oncology, Peter MacCallum Cancer Centre, University of Melbourne, Melbourne, VIC, Australia., Department of Radiation Oncology, Calvary Mater Newcastle, Waratah, NSW, Australia; School of Medicine and Public Health, University of Newcastle, Callaghan, NSW, Australia.