193 - Quality of Life Results from NRG-GU005: A Phase III Trial of SBRT vs. Hypofractionated IMRT for Localized Intermediate Risk Prostate Cancer

10:45am - 10:55am PT

Room 156/158

Presenter(s)

James Yu, MD, FASTRO, MHS - Dartmouth Hitchcock Medical Center, Lebanon, NH

J. B. Yu¹, S. Pugh², R. J. Ellis III³, F. Y. Feng⁴, A. J. Frazier⁵, J. D. Pennington⁶, J. M. Michalski⁷, D. E. Spratt⁸, M. Ghilezan⁹, S. C. Morgan¹⁰, A. M. Mihai¹¹, A. A. Solanki¹², A. Amjad¹³, M. W. Straza Jr¹⁴, C. Menard¹⁵, T. M. Schroeder¹⁶, D. T. Marshall¹⁷, R. Paulus¹⁸, and H. M. Sandler¹⁹; ¹Department of Radiation Oncology and Applied Sciences, Dartmouth Geisel School of Medicine, Lebanon, NH, ²The American College of Radiology, Philadelphia, PA, ³University of South Florida/Tampa GeneralHospital, Tampa, FL, ⁴Department of Radiation Oncology, University of California San Francisco, San Francisco, CA, ⁵McLaren Cancer Institute-Macomb, Mount Clemens, MI, ⁶Southeast Clinical Oncology Research Consortium NCORP, Richmond, VA, ⁷Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, ⁸Case Western Reserve University, Cleveland, OH, ⁹Michigan Healthcare Professionals, Detroit, MI, ¹⁰The Ottawa Hospital Cancer Centre, Ottawa, ON, Canada, ¹¹Beacon Hospital and Cancer Trials Ireland, Dublin, Ireland, ¹²Department of Radiation Oncology, Stritch School of Medicine, Cardinal Bernardin Cancer Center, Loyola University Chicago, Maywood, IL, ¹³Allan Blair Cancer Centre, Regina, SK, Canada, ¹⁴Department of Radiation Oncology, Froedtert & the Medical College of Wisconsin, Milwaukee, WI, ¹⁵Département de radio-oncologie, Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada, ¹⁶University of New Mexico Comprehensive Cancer Center, Albuquerque, NM, ¹⁷Medical University of South Carolina - Hollings Cancer Center, Charleston, SC, ¹⁸The American College of Radiology, Philidelphia, PA, ¹⁹Cedars-Sinai Medical Center, Los Angeles, CA

Purpose/Objective(s): NRG-GU005 was a randomized non-blinded phase III trial comparing image-guided stereotactic body radiation therapy (SBRT) to moderately hypofractionated intensity-modulated radiation therapy (MH-IMRT) in localized intermediate risk prostate cancer patients. We report on secondary objectives testing the hypothesis that HRQOL would be improved with SBRT.

Materials/Methods: Patients with localized prostate cancer were randomized 1:1 to receive either SBRT (36.25 Gy in 5 fractions) or MH-IMRT (either 70 Gy in 28 fractions or 60 Gy in 20 fractions), stratifying by risk group utilizing Gleason score and PSA and the use of rectal balloons and/or hydrogel rectal spacers. The Expanded Prostate Cancer Index Composite (EPIC-26) questionnaire was administered at baseline, 12, and 24 months post-treatment. Secondary PRO endpoints included the incidence of minimal clinically important decline (MCID) in EPIC-26 urinary irritative/obstructive (UIO) and bowel domains 1 year post treatment, and urinary incontinence (UI), sexual, and hormonal domains at 1 and 2 years post treatment. MCID was predetermined as >5 points for UIO, > 6 for UI, > 10 for sexual, and > 4 points for bowel and hormonal domains.

A repeated measures mixed effects model was conducted for each domain of EPIC-26, adjusting for baseline domain score, treatment arm, stratification factors, T-stage, age, and race.

Results: Baseline EPIC scores were similar between arms. At 1-year post-treatment there were significantly fewer patients in the SBRT arm as compared to the MH-IMRT arm with MCID in bowel (33% vs. 46%, p=0.002) and sexual domains (34% vs. 44%, p=0.026). At 2 years, there were significantly fewer patients in the SBRT arm (vs. MH-IMRT) with MCID in the UI domain (26% vs. 35%, p=0.023). Longitudinal analysis of the urinary incontinence domain showed significant treatment effect in favor of SBRT (least square mean difference=2.91, 95% confidence interval: 0.85-4.97, p=0.0058), however the sexual and hormonal domains did not see a significant treatment effect. Baseline function was significantly associated with higher subsequent domain scores for UI, sexual, and hormonal domains (p<0.0001). There were no significant associations between risk group or use of rectal balloons and/or hydrogel rectal spacers with UI, sexual, or hormonal domains.

Conclusion: Significantly fewer SBRT patients as compared to MH-IMRT patients experienced clinically important declines in sexual and bowel health-related quality of life (HRQOL) at 1 year and UI HRQOL at 2 years post-treatment, suggesting improvement in HRQOL with SBRT as compared to IMRT. The co-primary endpoints of 2-year bowel and UIO HRQOL and corresponding longitudinal models are reported separately.