title: Toxicity report of once weekly radiation therapy for low-risk prostate adenocarcinoma: preliminary results of a phase I/II trial.
abstract: BACKGROUND
  Increasing clinical data supports a low α/β ratio for prostate adenocarcinoma, potentially lower than that of surrounding normal tissues. A hypofractionated, weekly radiation therapy (RT) schedule should result in improved tumour control, reduced acute toxicity, and similar or decreased late effects. We report the toxicity profile of such treatment.
  
  
  METHODS
  We conducted a multi-institution phase I/II trial of three-dimensional conformal radiation therapy (3D-CRT) for favourable-risk prostate cancer (T1a-T2a, Gleason ≤ 6 and PSA < 10 ng/ml). RT consisted of 45 Gy in nine 5 Gy fractions, once weekly. Primary end-points were feasibility and late gastrointestinal (GI) toxicity (RTOG scale), while secondary end-points included acute GI toxicity, acute and late genitourinary (GU) toxicity, biochemical control, and survival.
  
  
  RESULTS
  Between 2006 and 2008, 80 patients were treated. No treatment interruptions occurred. The median follow-up is 33 months (range: 20-51). Maximal grade 1, 2, and 3 acute (< 3 months) GU toxicity was 29%, 31% and 5% respectively (no grade 4). Acute GI grade 1 toxicity was reported in 30% while grade 2 occurred in 14% (no grade 3 or 4). Crude late grade ≥ 3 toxicity rates at 31 months were 2% for both GU and GI toxicity. Cumulative late grade ≥ 3 GI toxicity at 3 years was 11%. Two patients had PSA failure according to the Phoenix definition. The three-year actuarial biochemical control rate is 97%.
  
  
  CONCLUSIONS
  Weekly RT with 45 Gy in 9 fractions is feasible and results in comparable toxicity. Long term tumour control and survival remain to be assessed.
authors: Department of Radiation Oncology, Hôpital Maisonneuve-Rosemont, Montréal, Québec, Canada.
authors: Cathy
authors: C
authors: Menkarios
authors: Éric
authors: É
authors: Vigneault
authors: Nicolas
authors: N
authors: Brochet
authors: David H A
authors: DH
authors: Nguyen
authors: Jean-Paul
authors: JP
authors: Bahary
authors: Marjory
authors: M
authors: Jolicoeur
authors: Marie-Claude
authors: MC
authors: Beauchemin
authors: Hugo
authors: H
authors: Villeneuve
authors: Thu
authors: T
authors: Van Nguyen
authors: Bernard
authors: B
authors: Fortin
authors: Carole
authors: C
authors: Lambert
mesh_terms: D000230:Adenocarcinoma / Q000532:radiotherapy*; D000328:Adult; D019583:Dose Fractionation, Radiation; D005500:Follow-Up Studies; D041981:Gastrointestinal Tract / Q000528:radiation effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011829:Radiation Dosage; D011878:Radiotherapy / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal / Q000379:methods*; D012306:Risk; D018401:Sample Size; D016896:Treatment Outcome