Related Experiment Video
Updated: Jun 6, 2025
Proton Therapy Delivery and Its Clinical Application in Select Solid Tumor Malignancies
Published on: February 6, 2019
Five-Year Prostate-Specific Membrane Antigen Positron Emission Tomography-Based Outcomes of Spot-Scanning Proton
Will Sperduto1, Molly M Voss2, Brady Laughlin1
1Department of Radiation Oncology, Mayo Clinic, Phoenix, Arizona.
Purpose:
We report 5-year oncologic outcomes of a prospective series of patients with prostate cancer treated with spot-scanning proton therapy (SSPT).
Methods And Materials:
A prospective registry identified patients with prostate cancer treated with SSPT between January 2016 and December 2018. Five-year overall survival, local control, biochemical failure, regional and distant failures, and adverse events (AEs) were assessed. Biochemical failure was defined as rise in prostate-specific antigen ≥ 2.0 ng/mL above nadir prostate-specific antigen. Baseline-adjusted toxicities were assigned using the Common Terminology Criteria for Adverse Events version 5.0.
Results:
With a median follow-up of 4.4 years, 284 patients with prostate cancer were treated with SSPT. Median total radiation dose was 79.2 Gy over 44 fractions, 70 Gy over 28 fractions, and 38 Gy over 5 fractions for conventional fractionation (CF), hypofractionation (HF), and stereotactic body radiation therapy (SBRT), respectively. Biochemical failure rate for all patients was 6.7%. Five-year local control rates for CF, HF, and SBRT were 100%, 100%, and 97.3%, respectively (P = .07). Regional recurrences occurred in 12 (4.2%) patients: 8 treated with CF, 2 with HF, and 2 with SBRT (P = .62). Distant failures occurred in 12 patients (4.2%): 5 treated with CF, 7 with HF, and none with SBRT (P = .05). Five-year overall survival for patients treated with CF, HF, and SBRT SSPT were 88.1%, 86.1%, and 97.2%, respectively (P = .1). Acute and chronic grade 2+ gastrointestinal AEs occurred in 8 (2.8%) and 51 (18.0%) patients, respectively. Acute and chronic grade 3+ gastrointestinal AEs occurred in 3 (1.1%) and 4 (1.4%) patients, respectively. Acute and chronic grade 2+ genitourinary-related AEs were observed in 71 (25%) and 63 (22.2%) patients, respectively. Acute and chronic grade 3+ genitourinary toxicity were observed in 3 (1.1%) and 6 (2.1%) patients, respectively.
Conclusions:
SSPT provides high local control rates and excellent oncologic outcomes across different fractionation schedules with low long-term AE rates.
