1. Long-term Outcomes from a Phase 1 Dose Escalation Study Using Stereotactic Body Radiotherapy for Patients with Low- or Intermediate-risk Prostate Cancer.
- Author
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Moore A, Kollmeier MA, McBride SM, Toumbacaris N, Zhang Z, Lacy-Elsayegh A, Dreyfuss A, Grossman CE, Gorovets D, and Zelefsky MJ
- Subjects
- Humans, Male, Aged, Middle Aged, Treatment Outcome, Aged, 80 and over, Prostate-Specific Antigen blood, Follow-Up Studies, Dose Fractionation, Radiation, Radiotherapy Dosage, Dose-Response Relationship, Radiation, Prostatic Neoplasms radiotherapy, Prostatic Neoplasms pathology, Prostatic Neoplasms surgery, Radiosurgery methods, Radiosurgery adverse effects
- Abstract
Background: Ultrahypofractionated stereotactic body radiation therapy (SBRT) has become a standard treatment intervention for localized prostate cancer., Objective: To report final long-term tumor control outcomes and late gastrointestinal (GI) and genitourinary (GU) toxicities from a single-center phase 1 dose escalation study using SBRT for patients with low- or intermediate-risk prostate cancer., Design, Setting and Participants: Between 2009 and 2012, 136 patients were enrolled and treated. The initial dose level was 32.5 Gy in five fractions. Doses were then sequentially escalated to 35 Gy, 37.5 Gy, and 40 Gy in five fractions delivered every other day., Outcome Measurements and Statistical Analysis: The primary endpoint was late treatment-related toxicity. Secondary endpoints included prostate-specific antigen (PSA) failure., Results and Limitations: The median follow-up was 10.5 yr for the 32.5-Gy group, 9.9 yr for the 35-Gy group, 8.2 yr for the 37.5-Gy group, and 7.3 yr for the 40-Gy group. The 8-yr cumulative incidence of PSA failure was 26% for 32.5 Gy, 15% for 35 Gy, 3.4% for 37.5 Gy, and 6.6% for 40 Gy. Higher radiation dose (37.5-40 Gy) and favorable intermediate risk (vs unfavorable intermediate risk) were associated with better PSA recurrence rates (p = 0.011 and 0.002, respectively). The 8-yr actuarial probability rates for survival free from late grade ≥2 toxicity were 94% for GI toxicity and 86% for GU toxicity. No grade 4 events were recorded. Higher dose levels were not associated with higher rates of late grade ≥2 GI (p = 0.2) or GU (p > 0.9) toxicity., Conclusions: SBRT doses ranging from 32.5 to 40 Gy were associated with low incidence of moderate or severe toxicities. Higher doses resulted in superior disease control outcomes 8 yr after treatment., Patient Summary: We investigated the association between the radiotherapy dose used and the rate of control of prostate cancer. We found that higher doses resulted in more favorable outcomes without excess toxicity. This trial is registered on ClinicalTrials.gov as NCT00911118., (Copyright © 2023 European Association of Urology. Published by Elsevier B.V. All rights reserved.)
- Published
- 2024
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