238 - The Role of Stereotactic Body Radiotherapy in Oligoprogressive Prostate Cancer: A Site-Specific Analysis of the Prospective, Phase II RADIANT Trial
Presenter(s)
K. M. Ruicci1,2, A. Barry3,4, X. Y. Ye5, P. Chung2,6, A. Berlin2,6, C. Catton2,6, E. Gutierrez2,6, A. Mesci2,6, A. McPartlin2,6, S. Raman7,8, J. Winter6,9, J. Dang6, N. Fallah-Rad10,11, V. Kumar10,11, D. Jiang10,11, S. S. Sridhar10,11, J. Helou12,13, and R. Glicksman2,6; 1Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, ON, Canada, 2Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada, 3University College Cork, Cork, Ireland, 4Cork University Hospital, Cork, Ireland, 5Department of Biostatistics, University Health Network, Toronto, ON, Canada, 6Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, ON, Canada, 7Radiation Oncology, BC Cancer, Toronto, ON, Canada, 8Department of Surgery, The University of British Columbia, Toronto, ON, Canada, 9Department of Medical Physics, Princess Margaret Cancer Centre, Toronto, ON, Canada, 10Division of Medical Oncology and Hematology, Princess Margaret Cancer Centre, Toronto, ON, Canada, 11Department of Medicine, University of Toronto, Toronto, ON, Canada, 12Division of Radiation Oncology, Western University, London, ON, Canada, 13Verspeeten Family Cancer Centre, London Health Sciences Centre, London, ON, Canada
Purpose/Objective(s): Changing to next-line systemic therapy is the standard of care for patients with progressive metastatic prostate cancer. However, to preserve systemic therapy options and minimize toxicity, stereotactic body radiation therapy (SBRT) is being increasingly considered for patients with limited disease progression (‘oligoprogression’). Here we analyze clinical, toxicity and quality of life (QOL) data for an oligoprogressive prostate cancer cohort from the prospective RADIANT clinical trial.
Materials/Methods: RADIANT (NCT04122469) was a single-arm, phase II basket trial which included patients with metastatic prostate cancer who had been on systemic therapy >3 months, with radiographic evidence of oligoprogression in <5 sites. Analysis by disease site was planned a priori. Patients received SBRT in 1 to 5 fractions to all progressive sites and were maintained on their current systemic therapy. The primary endpoint was cumulative incidence of change in systemic therapy, estimated with the Aalen-Johnson method. Secondary endpoints included local and distant failure (LF, DF), progression-free survival (PFS), overall survival (OS), toxicity and health-related (HR) QOL. Univariate Fine and Gray competing risk models were applied to examine associations between clinical characteristics and oncologic outcomes. A 2-sided p-value of <0.05 was considered statistically significant.
Results: Thirty-two patients were analyzed, with a median age of 74.0 years, median PSA of 6.7 µg/L, 25% with visceral metastases and a median of 2 prior lines of systemic therapy. The median follow-up time was 14.1 months (range 4.8 - 51.9 months). At 1 year, 55.1% of patients remained on the same systemic therapy line and local control was 84.0%. The cumulative incidence of grade 2 toxicity was 25.0% (95% CI, 13.6 - 46.1%) at 1 year, with no grade 3+ toxicities. HRQOL was maintained, with no detriment following SBRT delivery.
Conclusion: Among patients with oligoprogressive prostate cancer, SBRT is an effective and safe intervention, including in patients with classically aggressive disease features. Larger, randomized trials are needed to validate these findings.