title: Clinical and dosimetric predictors of late rectal syndrome after 3D-CRT for localized prostate cancer: preliminary results of a multicenter prospective study.
abstract: OBJECTIVE
  To assess the predictors of late rectal toxicity in a prospectively investigated group of patients treated at 70-80 Gy for prostate cancer (1.8-2 Gy fractions) with three-dimensional conformal radiotherapy.
  
  
  METHODS
  A total of 1,132 patients were entered into the study between 2002 and 2004. Three types of rectal toxicity, evaluated by a self-administered questionnaire, mainly based on the subjective objective management, analytic late effects of normal tissue system, were considered: stool frequency/tenesmus/pain, fecal incontinence, and bleeding. The data from 506 patients with a follow-up of 24 months were analyzed. The correlation between a number of clinical and dosimetric parameters and Grade 2 or greater toxicity was investigated by univariate and multivariate (MVA) logistic analyses.
  
  
  RESULTS
  Of the 1,132 patients, 21, 15, and 30 developed stool frequency/tenesmus/pain, fecal incontinence, and bleeding, respectively. Stool frequency/tenesmus/pain correlated with previous abdominal/pelvic surgery (MVA, p=0.05, odds ratio [OR], 3.3). With regard to incontinence, MVA showed the volume receiving>or=40 Gy (V40) (p=0.035, OR, 1.037) and surgery (p=0.02, OR, 4.4) to be the strongest predictors. V40 to V70 were highly predictive of bleeding; V70 showed the strongest impact on MVA (p=0.03), together with surgery (p=0.06, OR, 2.5), which was also the main predictor of Grade 3 bleeding (p=0.02, OR, 4.2).
  
  
  CONCLUSIONS
  The predictive value of the dose-volume histogram was confirmed for bleeding, consistent with previously suggested constraints (V50<55%, V60<40%, V70<25%, and V75<5%). A dose-volume histogram constraint for incontinence can be suggested (V40<65-70%). Previous abdominal/pelvic surgery correlated with all toxicity types; thus, a modified constraint for bleeding (V70<15%) can be suggested for patients with a history of abdominal/pelvis surgery, although further validation on a larger population with longer follow-up is needed.
authors: Department of Medical Physics, Ospedale San Raffaele, Milan, Italy. fiorino.claudio@hsr.it
authors: Claudio
authors: C
authors: Fiorino
authors: Gianni
authors: G
authors: Fellin
authors: Tiziana
authors: T
authors: Rancati
authors: Vittorio
authors: V
authors: Vavassori
authors: Carla
authors: C
authors: Bianchi
authors: Valeria Casanova
authors: VC
authors: Borca
authors: Giuseppe
authors: G
authors: Girelli
authors: Marco
authors: M
authors: Mapelli
authors: Loris
authors: L
authors: Menegotti
authors: Simona
authors: S
authors: Nava
authors: Riccardo
authors: R
authors: Valdagni
mesh_terms: D000005:Abdomen / Q000601:surgery; D000704:Analysis of Variance; D003248:Constipation / Q000209:etiology; D003672:Defecation; D005242:Fecal Incontinence / Q000209:etiology; D006471:Gastrointestinal Hemorrhage / Q000209:etiology; D006801:Humans; D008297:Male; D016017:Odds Ratio; D010388:Pelvis / Q000601:surgery; D011183:Postoperative Complications; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000150:complications*; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000009:adverse effects*; D012007:Rectum / Q000528:radiation effects*; D011795:Surveys and Questionnaires