Ultrahypofractionated Intensity Modulated Proton Therapy for Prostate Cancer: An Institutional Experience
Faculty and Abstracts
Purpose: To describe our clinical experience and assess outcomes for patients treated with ultrahypofractionated intensity modulated proton therapy (IMPT).
Methodology: A retrospective analysis was performed of patient records who were treated with definitive ultrahypofractionated IMPT at a single institute between July 2019 and August 2023. Kaplan-Meier analysis was used for biochemical progression-free survival (bPFS) estimation. Toxicity data as described in the patient chart was collected.
Results: 109 patients were identified for analysis, receiving treatment between July 2019 to August 2023. 7 (6%) had very low/low risk disease, 40 (37%) had favorable intermediate risk disease, 40 (37%) had unfavorable intermediate risk disease, and 20 (18%) had high risk disease. 2 (2%) had metastatic disease. Patients received 5 fractions of ultrahypofractionated IMPT (modal dose of 36.25 Gy in 5 fractions typically delivered every other day). The median follow-up was 15.0 months. One patient experienced biochemical failure at 8.1 months. There were no observed deaths. The estimated bPFS was 98.7% at 2 years. Mean PSA nadir was 0.69. Acute grade 1-2 toxicity was experienced in 64 patients (59%). Late grade 1-2 toxicity was observed in 41 patients (38%). Neither acute nor late grade 3+ toxicity was observed in any patient.
Conclusions: This retrospective study demonstrated excellent disease control with low associated toxicity in patients treated with ultrahypofractionated IMPT for all risk groups of prostate cancer.
