title: Acute toxicity and its dosimetric correlates for high-risk prostate cancer treated with moderately hypofractionated radiotherapy.
abstract: OBJECTIVE
  To report the acute toxicity and the dosimetric correlates after moderately hypofractionated radiotherapy for localized prostate cancer.
  
  
  METHODS
  A total of 101 patients with localized prostate cancer were treated with image-guided intensity-modulated radiation therapy. Patients were treated to 65Gy/25Fr/5 weeks (n = 18), or 60Gy/20Fr/4 weeks (n = 83). Most (82.2%) had high-risk or pelvic node-positive disease. Acute toxicity was assessed using Radiation Therapy Oncology Group (RTOG) acute morbidity scoring criteria. Dose thresholds for acute rectal and bladder toxicity were identified.
  
  
  RESULTS
  The incidence of acute grade 2 GI toxicity was 20.8%, and grade 2 genitourinary (GU) toxicity was 6.9%. No Grade 3 to 4 toxicity occurred. Small bowel toxicity was uncommon (Gr 2 = 4%). The 2Gy equivalent doses (EQD2) to the rectum and bladder (α/β = 3) calculated showed that the absolute doses were more consistent predictors of acute toxicities than the relative volumes. Those with grade 2 or more GI symptoms had significantly higher VEQD2-60Gy(13.2 vs 9.9cc, p = 0.007) and VEQD2-50Gy(20.6 vs 15.4cc, p = 0.005). Those with grade 2 or more GU symptoms had significantly higher VEQD2-70Gy(30.4 vs 18.4cc, p = 0.001) and VEQD2-65Gy(44.0 vs 28.8cc, p = 0.001). The optimal cutoff value for predicting grade 2 acute proctitis, for VEQD2-60Gywas 9.7cc and for VEQD2-50Gywas 15.9cc. For grade 2 GU symptoms, the threshold values were 23.6cc for VEQD2-70Gyand 38.1cc for VEQD2-65Gy.
  
  
  CONCLUSIONS
  Hypofractionated radiotherapy for prostate cancer is well tolerated and associated with manageable acute side effects. The absolute dose-volume parameters of rectum and bladder predict for acute toxicities.
authors.affiliation: Department of Radiation Oncology, Tata Medical Center, Kolkata, India.
authors.forename: Moses
authors.initials: M
authors.lastname: Arunsingh
authors.affiliation: Department of Radiation Oncology, Tata Medical Center, Kolkata, India. Electronic address: imallick@gmail.com.
authors.forename: Indranil
authors.initials: I
authors.lastname: Mallick
authors.affiliation: Department of Radiation Oncology, Tata Medical Center, Kolkata, India.
authors.forename: Sriram
authors.initials: S
authors.lastname: Prasath
authors.affiliation: Department of Radiation Oncology, Tata Medical Center, Kolkata, India.
authors.forename: B
authors.initials: B
authors.lastname: Arun
authors.affiliation: Department of Radiation Oncology, Tata Medical Center, Kolkata, India.
authors.forename: Sandip
authors.initials: S
authors.lastname: Sarkar
authors.affiliation: Department of Radiation Oncology, Tata Medical Center, Kolkata, India.
authors.forename: Raj Kumar
authors.initials: RK
authors.lastname: Shrimali
authors.affiliation: Department of Radiation Oncology, Tata Medical Center, Kolkata, India.
authors.forename: Sanjoy
authors.initials: S
authors.lastname: Chatterjee
authors.affiliation: Department of Radiation Oncology, Tata Medical Center, Kolkata, India.
authors.forename: Rimpa
authors.initials: R
authors.lastname: Achari
mesh_terms: D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D000069473:Radiation Dose Hypofractionation; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects*; D012189:Retrospective Studies
keywords: Acute toxicity; Hypofractionated radiation therapy