Genitourinary Cancer

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SU_31_2316 - Dosimetry and Toxicity of a Phase I Clinical Trial of Men Treated for Prostate Cancer With Lattice Extreme Ablative Dose (LEAD) Radiation Therapy

Sunday, October 21
1:15 PM - 2:45 PM
Location: Innovation Hub, Exhibit Hall 3

Dosimetry and Toxicity of a Phase I Clinical Trial of Men Treated for Prostate Cancer With Lattice Extreme Ablative Dose (LEAD) Radiation Therapy
A. Pollack1, F. M. Chinea1, E. L. Bossart1, D. Kwon1, M. C. Abramowitz1, C. Lynne1, M. Jorda1, B. Marples1, V. Patel1, X. Wu1, I. M. Reis2, M. T. Studenski1, V. J. Casillas1, and R. Stoyanova1; 1University of Miami, Miami, FL, 2Department of Public Health Sciences, University of Miami/Sylvester C.Cancer Center, Miami, FL

Purpose/Objective(s): The hypothesis was that high doses above 10Gy to portions of the dominant tumor GTV(s), in combination with standard fractionated prostate radiotherapy immediately afterward, would result in enhanced tumor control due to bystander effects without increasing toxicity. Late toxicity and tumor control from such a high-dose spatially-fractionated approach is described herein.

Materials/Methods: Between 2011 - 2014, 25 men were treated for favorable to high-risk prostate cancer using 1-3 dosepipes (each 7 mm in diameter) to distinct multiparametric (mp)MRI-defined GTV(s) on the LEAD trial (LEAD, NCT01411319). The dosepipes were treated on day 1 with 12-14 Gy, following which the entire prostate, along with the proximal seminal vesicles (SVs), was treated to 76 Gy at 2 Gy/fraction. For high-risk patients, the distal SVs and pelvic lymph nodes received 56 Gy concurrently in the same 38 fractions could be treated (n=2). The total dose to the LEAD volume(s) was 88-90 Gy (149 Gy3.0 in 2.0 Gy equivalents). There were 14 patients treated with short term androgen deprivation therapy. Results: Median follow-up is 45 mo (range 9-63 mo). Dosimetric parameters were satisfactorily met. For genitourinary (GU) toxicity (definitely or probably related), 14 men had grade 1 and two had grade 2 events at baseline. During or within 3 mo of RT, there were 2 Grade 1 and one Grade 2. For late GU toxicity there were four Grade 1 and 13 Grade 2 (mostly urgency and frequency treated with alpha blockers); there were no grade 3 or above events. For gastrointestinal toxicity, during or within 3 mo of RT, there was one Grade 1 and one Grade 2 event. There were two grade 1 and three grade 2 events; there were no grade 3 or above events. A total of 8 patients underwent endpoint biopsy with all showing negative results. Two patients experienced biochemical failure with identifiable distant disease. No patient had a documented local failure. Conclusion: External beam radiotherapy delivered with an upfront spatially-fractionated, dose-escalated mpMRI-GTV(s) boost is feasible and was not associated with any unexpected events. The technique is now part of a follow-up Phase II randomized trial.

Author Disclosure: A. Pollack: Research Grant; Radiation Therapy Oncology Group, Varian Medical Systems. Honoraria; Mayo Clinic, City of Hope. Consultant; Medivation. Travel Expenses; Radiation Therapy Oncology Group, Mayo Clinic, Rio Oncology, Varian Medical Systems Inc, IBA Proton Therapy, City of Hope. F.M. Chinea: None. E.L. Bossart: None. D. Kwon: None. M.C. Abramowitz: None. C. Lynne: None. B. Marples: Editor; ASTRO. SEPD committee; ASTRO. X. Wu: None. I.M. Reis: None. M.T. Studenski: None. V.J. Casillas: None.

Alan Pollack, MD, PhD

University of Miami Sylvester Comprehensive Cancer Center

Disclosure:
Employment
University of Miami Miller School of Medicine: Chair and Professor of Radiation Oncology: Employee; University of Miami School of Medicine: Chair and Professor of Radiation Oncology: Employee

Compensation
City of Hope: Honoraria, Travel Expenses; Radiation Therapy Oncology Group: Research Grants, Travel Expenses; Varian: Research Grants; Varian Medical Systems: Research Grants

Biography:
Dr. Pollack is Professor and Chair of the Department of Radiation Oncology at the Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine. He obtained a Ph.D. in Microbiology and Immunology from the University of Miami and later graduated from the University of Miami Miller School of Medicine’s Ph.D. to M.D. program. He did an internal medicine internship at Jackson Memorial Hospital in Miami, before doing a residency in radiation oncology at U.T.-M.D. Anderson Cancer Center in Houston. While at M.D. Anderson, Dr. Pollack attained the rank of Professor, was Director of the Residency Training Program and was a co-leader of the GU group before assuming the Chair in Radiation Oncology position at Fox Chase Cancer Center in Philadelphia in 2001. He held that position for 7 years before returning to Miami as Chair and Professor of Radiation Oncology in 2008. He became interim Deputy Director of Sylvester in 2017. Dr. Pollack’s research interests have centered on the management of prostate cancer with radiotherapy, the role and length of androgen deprivation therapy, radiation dose escalation, radiation fractionation, small molecule/gene/viral vector targeted therapy, and tissue biopsy, liquid biopsy and imaging markers of outcome.

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