title: Hypofractionated Versus Standard Fractionated Proton-beam Therapy for Low-risk Prostate Cancer: Interim Results of a Randomized Trial PCG GU 002.
abstract: OBJECTIVE
  To identify differences in terms of quality of life, the American Urological Association Symptom Index (AUA), or adverse events (AEs) among patients with prostate cancer treated with either standard fractionation or hypofractionation proton-beam therapy.
  
  
  METHODS
  Patients were prospectively randomized to receive 38 Gy relative biological effectiveness (RBE) in 5 treatments (n=49) or 79.2 Gy RBE in 44 treatments (n=33). All patients had low-risk prostate cancer and were treated with proton therapy using fiducial markers and daily image guidance.
  
  
  RESULTS
  Median follow-up for both groups was 18 months; 33 patients had follow-up of 2 years or longer. Baseline median (range) AUA was 4.7 (0 to 13) for the 38 Gy RBE arm and 4.8 (0 to 17) for the 79.2 Gy RBE arm. We observed no difference between the groups regarding the Expanded Prostate Index Composite urinary, bowel, or sexual function scores at 3, 6, 12, 18, or 24 months after treatment. The only significant difference was the AUA score at 12 months (8 for the 38 Gy RBE arm vs. 5 for the 79.2 Gy RBE arm; P=0.04); AUA scores otherwise were similar between groups. No grade 3 or higher AEs occurred in either arm.
  
  
  CONCLUSIONS
  Patients treated with proton therapy in this randomized trial tolerated treatment well, with excellent quality-of-life scores, persistent low AUA, and no grade 3 or higher AEs on either arm. We showed no apparent clinical difference in outcomes with hypofractionated proton-beam therapy compared with standard fractionation on the basis of this interim analysis.
authors.affiliation: Department of Radiation Oncology, Mayo Clinic Hospital, Phoenix, AZ.
authors.forename: Carlos E
authors.initials: CE
authors.lastname: Vargas
authors.affiliation: CDH Proton Center.
authors.forename: William F
authors.initials: WF
authors.lastname: Hartsell
authors.affiliation: Proton Collaborative Group, Warrenville, IL.
authors.forename: Megan
authors.initials: M
authors.lastname: Dunn
authors.affiliation: Department of Radiation Oncology, Mayo Clinic Hospital, Phoenix, AZ.
authors.forename: Sameer R
authors.initials: SR
authors.lastname: Keole
authors.affiliation: Radiation Medicine Associates, PC, Radiation Oncology, Oklahoma City, OK.
authors.forename: Lucius
authors.initials: L
authors.lastname: Doh
authors.affiliation: Omega Statistics, Murrieta, CA.
authors.forename: Elaine
authors.initials: E
authors.lastname: Eisenbeisz
authors.affiliation: Radiation Medicine Associates, PC, Radiation Oncology, Oklahoma City, OK.
authors.forename: Gary L
authors.initials: GL
authors.lastname: Larson
mesh_terms: D000368:Aged; D018572:Disease-Free Survival; D019583:Dose Fractionation, Radiation; D004307:Dose-Response Relationship, Radiation; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009361:Neoplasm Invasiveness; D011471:Prostatic Neoplasms / Q000401:mortality / Q000473:pathology* / Q000532:radiotherapy*; D061766:Proton Therapy / Q000009:adverse effects / Q000379:methods*; D000069473:Radiation Dose Hypofractionation; D011832:Radiation Injuries / Q000517:prevention & control*; D011836:Radiation Tolerance; D018570:Risk Assessment; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States