title: Identification of a rectal subregion highly predictive of rectal bleeding in prostate cancer IMRT.
abstract: To identify rectal subregions at risks (SRR) highly predictive of 3-year rectal bleeding (RB) in prostate cancer IMRT.
  
  
  
  Overall, 173 prostate cancer patients treated with IMRT/IGRT were prospectively analyzed, divided into "training" (n=118) and "validation" cohorts (n=53). Dose-volume histograms (DVHs) were calculated in three types of rectal subregions: "geometric", intuitively defined (hemi-rectum,…); "personalized", obtained by non-rigid registration followed by voxel-wise statistical analysis (SRRp); "generic", mapped from SRRps, located within 8×8 rectal subsections (SRRg). DVHs from patients with and without RB were compared and used for toxicity prediction.
  
  
  
  Training cohort SRRps were primarily within the inferior anterior hemi-rectum and upper anal canal, with 3.8Gy mean dose increase for Grade⩾1 RB patients. The SRRg, representing 15% of the absolute rectal volume, was located in 10 inferior-anterior rectal subsections. V18-V70 for SRRps and V58-V65 for SRRg were significantly higher for RB patients than non-RB. Maximum areas under the curve (AUCs) for SRRp and SRRg RB prediction were 71% and 64%, respectively. The validation cohort confirmed the predictive value of SRRg for Grade⩾1 RB. The total cohort confirmed the predictive value of SRRg for Grade⩾2 RB. Geometrical subregions were not RB predictors.
  
  
  
  The inferior-anterior hemi anorectum was highly predictive of RB.
authors.affiliation: INSERM 1099, Rennes, France; LTSI, Université de Rennes 1, Rennes, France.
authors.forename: Gaël
authors.initials: G
authors.lastname: Dréan
authors.affiliation: INSERM 1099, Rennes, France; LTSI, Université de Rennes 1, Rennes, France.
authors.forename: Oscar
authors.initials: O
authors.lastname: Acosta
authors.affiliation: INSERM 1099, Rennes, France; LTSI, Université de Rennes 1, Rennes, France.
authors.forename: Juan D
authors.initials: JD
authors.lastname: Ospina
authors.affiliation: INSERM 1099, Rennes, France; LTSI, Université de Rennes 1, Rennes, France.
authors.forename: Auréline
authors.initials: A
authors.lastname: Fargeas
authors.affiliation: INSERM 1099, Rennes, France; LTSI, Université de Rennes 1, Rennes, France; Département de radiothérapie, Centre Eugène Marquis, Rennes, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Lafond
authors.affiliation: Département de radiothérapie, Centre Eugène Marquis, Rennes, France.
authors.forename: Gwenaelle
authors.initials: G
authors.lastname: Corrégé
authors.affiliation: Hôpital Henri Mondor, France; UPEC, Université Paris Est Créteil, France.
authors.forename: Jean-L
authors.initials: JL
authors.lastname: Lagrange
authors.affiliation: Centre Georges François Leclerc, Dijon, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Créhange
authors.affiliation: INSERM 1099, Rennes, France; LTSI, Université de Rennes 1, Rennes, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Simon
authors.affiliation: INSERM 1099, Rennes, France; LTSI, Université de Rennes 1, Rennes, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Haigron
authors.affiliation: INSERM 1099, Rennes, France; LTSI, Université de Rennes 1, Rennes, France; Département de radiothérapie, Centre Eugène Marquis, Rennes, France. Electronic address: r.de-crevoisier@rennes.unicancer.fr.
authors.forename: Renaud
authors.initials: R
authors.lastname: de Crevoisier
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D006471:Gastrointestinal Hemorrhage / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D058958:Organs at Risk; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects*; D012002:Rectal Diseases / Q000209:etiology*
keywords: Inverse planning; Prediction model; Prostate cancer radiotherapy; Rectal bleeding; Specific patient; Toxicity