title: Anatomical and clinical predictors of acute bowel toxicity in whole pelvis irradiation for prostate cancer with Tomotherapy.
abstract: OBJECTIVE
  Assessing predictors of acute bowel toxicity after whole-pelvis irradiation (WPRT) Image-guided Tomotherapy with simultaneous integrated boost on prostate/prostate bed.
  
  
  METHODS
  In the period March 2005-April 2009, 178 patients were treated with radical or adjuvant/salvage intent with WPRT Tomotherapy. Median dose to the pelvic nodes was 51.8 Gy/28 fractions while concomitantly delivering 65.5-74.2 Gy to prostate/prostatic bed. The impact of many anatomical and clinical parameters on ≥ Grade 2 acute bowel toxicity was investigated by logistic analyses.
  
  
  RESULTS
  Only 15/178 patients (8.4%) experienced Grade 2 toxicity (none Grade 3). Main predictors at univariate analysis were nodal CTV (CTVN ≥ 380 cc; OR: 3.7, p=0.017), treatment duration (< 40 days; OR: 6.2, p=0.006) and Grade 2 acute rectal toxicity (OR: 6.5, p=0.015). A multivariate analysis including only pre-treatment variables revealed an independent role of CTVN and age; if including treatment-related factors the best predictors were age, treatment duration and Grade 2 rectal toxicity. This last was correlated with the overlap between PTVN and loops (OVPN ≥ 51 cc; OR: 14.4, p=0.0003) that is representative of the volume of loops receiving the prescribed dose (51.8 Gy, 1.85 Gy/fr).
  
  
  CONCLUSIONS
  Acute bowel toxicity after WPRT Tomotherapy is mild, relatively rare and associated to larger CTVN and older age. While efforts to further reduce it do not appear to be relevant, the pre-treatment assessment of "high-risk" patients may help physicians in better managing symptoms. A prospective validation would be very important in confirming these results and in better refining dose-volume bowel effects including symptoms milder that the ones here investigated and retrospectively assessed.
authors.affiliation: Medical Physics, San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Longobardi
authors.forename: Genoveffa
authors.initials: G
authors.lastname: Berardi
authors.forename: Claudio
authors.initials: C
authors.lastname: Fiorino
authors.forename: Filippo
authors.initials: F
authors.lastname: Alongi
authors.forename: Cesare
authors.initials: C
authors.lastname: Cozzarini
authors.forename: Aniko
authors.initials: A
authors.lastname: Deli
authors.forename: Mariangela
authors.initials: M
authors.lastname: La Macchia
authors.forename: Lucia
authors.initials: L
authors.lastname: Perna
authors.forename: Nadia Gisella
authors.initials: NG
authors.lastname: Di Muzio
authors.forename: Riccardo
authors.initials: R
authors.lastname: Calandrino
mesh_terms: D000368:Aged; D006801:Humans; D007422:Intestines / Q000528:radiation effects*; D016015:Logistic Models; D008297:Male; D010388:Pelvis / Q000528:radiation effects*; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000209:etiology*; D011879:Radiotherapy Dosage; D061089:Radiotherapy, Image-Guided