Five-year outcomes from 3 prospective trials of image-guided proton therapy for prostate cancer

Int J Radiat Oncol Biol Phys. 2014 Mar 1;88(3):596-602. doi: 10.1016/j.ijrobp.2013.11.007.


Purpose: To report 5-year clinical outcomes of 3 prospective trials of image-guided proton therapy for prostate cancer.

Methods and materials: A total of 211 prostate cancer patients (89 low-risk, 82 intermediate-risk, and 40 high-risk) were treated in institutional review board-approved trials of 78 cobalt gray equivalent (CGE) in 39 fractions for low-risk disease, 78 to 82 CGE for intermediate-risk disease, and 78 CGE with concomitant docetaxel therapy followed by androgen deprivation therapy for high-risk disease. Toxicities were graded according to Common Terminology Criteria for Adverse Events (CTCAE), version 3.0. Median follow-up was 5.2 years.

Results: Five-year rates of biochemical and clinical freedom from disease progression were 99%, 99%, and 76% in low-, intermediate-, and high-risk patients, respectively. Actuarial 5-year rates of late CTCAE, version 3.0 (or version 4.0) grade 3 gastrointestinal and urologic toxicity were 1.0% (0.5%) and 5.4% (1.0%), respectively. Median pretreatment scores and International Prostate Symptom Scores at >4 years posttreatment were 8 and 7, 6 and 6, and 9 and 8, respectively, among the low-, intermediate-, and high-risk patients. There were no significant changes between median pretreatment summary scores and Expanded Prostate Cancer Index Composite scores at >4 years for bowel, urinary irritative and/or obstructive, and urinary continence.

Conclusions: Five-year clinical outcomes with image-guided proton therapy included extremely high efficacy, minimal physician-assessed toxicity, and excellent patient-reported outcomes. Further follow-up and a larger patient experience are necessary to confirm these favorable outcomes.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antineoplastic Agents, Hormonal / therapeutic use
  • Disease Progression
  • Dose Fractionation, Radiation
  • Humans
  • Male
  • Middle Aged
  • Prospective Studies
  • Prostate-Specific Antigen / blood
  • Prostatic Neoplasms / blood
  • Prostatic Neoplasms / drug therapy
  • Prostatic Neoplasms / mortality
  • Prostatic Neoplasms / radiotherapy*
  • Proton Therapy / adverse effects
  • Proton Therapy / methods*
  • Radiotherapy Planning, Computer-Assisted
  • Radiotherapy, Image-Guided / methods*
  • Time Factors
  • Treatment Outcome


  • Antineoplastic Agents, Hormonal
  • Prostate-Specific Antigen