Main Session
Sep
29
PQA 06 - Genitourinary Cancer, Gynecological Cancer, and Health Care Access and Engagement
3265 - Intensity Modulated Proton Therapy (IMPT) for Localized Prostate Cancer: Disease Control Outcomes in Intermediate to Very-High Risk Patients
Presenter(s)
Marcio Fagundes, MD - Miami Cancer Institute, Miami, FL
M. A. Fagundes1,2, H. Hassan1, M. A. M. Rodrigues1,2, A. Kaiser1,2, Y. Weiss1,2, A. Gutierrez1,2, A. Wroe1,2, C. Tohtz1, J. Wohl1, S. Yarlagadda1, M. M. Zerey1, O. Gal1, D. Pilla1, and M. P. Mehta1,2; 1Department of Radiation Oncology, Miami Cancer Institute, Baptist Health South Florida, Miami, FL, 2Department of Oncological Sciences, Herbert Wertheim College of Medicine, Florida International University, Miami, FL
Purpose/Objective(s):
Proton therapy (PT) is increasingly employed as a radiation modality for localized prostate cancer. Pencil beam scanning has emerged as a tool to improve organ at risk sparing and allow inclusion of pelvic nodal treatment for eligible patients at risk for nodal involvement. This study reports the effectiveness of PT in intermediate to very-high risk localized prostate cancer.Materials/Methods:
Between 01/18 and 12/23, 404 patients were treated with high-dose IMPT to prostate and seminal vesicles (SV) with full dose to SV proximal or positive when applicable, as well as elective nodes. Disease risk group were stratified following National Comprehensive Cancer Network guidelines as follows: favorable-intermediate (FIR), 55 (13.6%); unfavorable-intermediate (UIR), 116 (28.7%); high-risk (HR), 154 (38.1%); and very-high (VHR), 79 (19.6%). Biochemical failure was defined by the Phoenix Consensus as a post-treatment nadir PSA level +2 ng/mL. Descriptive statistics and Kaplan-Meier estimates were used to assess survival outcomes.Results:
Median age was 73 years. Median follow-up was 51 months. Total dose was 78 Gy in 39 fractions for 271 (67.1%), 70 Gy in 28 fractions for 125 (30.9%), and 60 Gy in 20 fractions for 8 (2%). We utilized elective pelvic nodal irradiation in a significant majority, 124 (80.5%) HR and in 79 (100%) VHR to a median dose of 48.6 Gy in 27 fractions (range 44-50.4 Gy). Similarly, androgen deprivation therapy was employed in the majority, 77.6% (UIR), 92.2% (HR) and 100% (VHR). Freedom from biochemical relapse rates at 5-years and 7-years were 100% and 100% for FIR, 97% and 97% for UIR, 93.4% and 82.2% for HR and 89.3% and 71.1% for VHR, respectively. Only 2 UIR patients had biochemical recurrence while none of the FIR relapsed to date. The corresponding overall survival rates at 5 years and 7 years were 92.2% and 92.2% for FIR, 94% and 94% for UIR, 92.2% and 92.2% for HR and 93.9% and 75.1% for VHR, respectively. The overall 5-year and 7-year prostate cancer-specific survival was 98.9%; only two patients died of disease, both in HR group, at 50 and 58-months post-RT.Conclusion:
Proton therapy for localized prostate cancer showed excellent disease control compared to contemporary cohorts. Whether our data represent the actual benefit of prophylactic nodal RT especially in VHR patients or stage migration due to the advent of PSMA PET scanning is the subject of further inquiry.