title: Dose-escalation of five-fraction SABR in prostate cancer: Toxicity comparison of two prospective trials.
abstract: OBJECTIVE
  To compare biochemical outcome and toxicities of two prospective 5-fraction stereotactic ablative radiotherapy (SABR) studies in prostate cancer.
  
  
  METHODS
  84 patients in pHART3 received 35 Gy, 30 patients in pHART6 received 40 Gy in 5-fractions to the prostate alone, once weekly. 4mm and 5mm PTV margins were used, respectively. Biochemical outcome, acute, late and cumulative genitourinary (GU)/gastrointestinal (GI) toxicities were compared.
  
  
  RESULTS
  Median follow-up was 74 and 36 months, respectively. Median prostate specific antigen nadir was 0.4 ng/ml and 0.3 ng/ml. 2-, 4- and 6-year biochemical relapse-free survival (bRFS-2+nadir) was 100%, 98.7% and 95.9% in pHART3; 100%, 100% and not reached in pHART6 (p=0.91). There was one acute grade 3 GU (retention) and late grade 4 GI (fistula) toxicity in pHART3, none in pHART6. One patient in each study had persisting grade 2+ toxicity at the last follow-up. pHART6 patients had a greater grade 2+ cumulative GU (5% versus 24.2%) and GI (7.6% versus 26.2%) toxicities.
  
  
  CONCLUSIONS
  Patients receiving dose-escalated SABR had slightly lower PSA nadir and similar bRFS, longer follow-up is needed to better estimate biochemical outcomes. There was a greater risk of grade 2 toxicity in pHART6 but not grade 3+ toxicities. Persisting toxicity at the last follow-up is similar.
authors.affiliation: Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, Canada; Department of Radiation Oncology, University of Toronto, Canada.
authors.forename: H Bindu
authors.initials: HB
authors.lastname: Musunuru
authors.affiliation: Department of Radiation Oncology, CancerCare Manitoba, Canada.
authors.forename: Harvey
authors.initials: H
authors.lastname: Quon
authors.affiliation: Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, Canada; Department of Medical Physics, Odette Cancer Centre, Canada.
authors.forename: Melanie
authors.initials: M
authors.lastname: Davidson
authors.affiliation: Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, Canada; Department of Radiation Oncology, University of Toronto, Canada.
authors.forename: Patrick
authors.initials: P
authors.lastname: Cheung
authors.affiliation: MacroStat, Inc, Toronto, Canada.
authors.forename: Liying
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, Canada; Department of Radiation Oncology, University of Toronto, Canada.
authors.forename: Laura
authors.initials: L
authors.lastname: D'Alimonte
authors.affiliation: Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, Canada.
authors.forename: Andrea
authors.initials: A
authors.lastname: Deabreu
authors.affiliation: Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, Canada.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Mamedov
authors.affiliation: Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, Canada; Department of Radiation Oncology, University of Toronto, Canada; Institute of Health Policy, Measurement and Evaluation, University of Toronto, Canada. Electronic address: andrew.loblaw@sunnybrook.ca.
authors.forename: Andrew
authors.initials: A
authors.lastname: Loblaw
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019583:Dose Fractionation, Radiation; D005767:Gastrointestinal Diseases / Q000209:etiology; D006801:Humans; D008297:Male; D052801:Male Urogenital Diseases / Q000209:etiology; D008875:Middle Aged; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000209:etiology; D016634:Radiosurgery / Q000009:adverse effects* / Q000379:methods
chemical_list: D017430:Prostate-Specific Antigen
keywords: Image-guided radiotherapy; Prostate cancer; Stereotactic ablative radiotherapy; Toxicity