title: Normal tissue complication probability analysis of acute gastrointestinal toxicity in cervical cancer patients undergoing intensity modulated radiation therapy and concurrent cisplatin.
abstract: OBJECTIVE
  To test the hypothesis that increased bowel radiation dose is associated with acute gastrointestinal (GI) toxicity in cervical cancer patients undergoing concurrent chemotherapy and intensity-modulated radiation therapy (IMRT), using a previously derived normal tissue complication probability (NTCP) model.
  
  
  METHODS
  Fifty patients with Stage I-III cervical cancer undergoing IMRT and concurrent weekly cisplatin were analyzed. Acute GI toxicity was graded using the Radiation Therapy Oncology Group scale, excluding upper GI events. A logistic model was used to test correlations between acute GI toxicity and bowel dosimetric parameters. The primary objective was to test the association between Grade ≥2 GI toxicity and the volume of bowel receiving ≥45 Gy (V(45)) using the logistic model.
  
  
  RESULTS
  Twenty-three patients (46%) had Grade ≥2 GI toxicity. The mean (SD) V(45) was 143 mL (99). The mean V(45) values for patients with and without Grade ≥2 GI toxicity were 176 vs. 115 mL, respectively. Twenty patients (40%) had V(45) >150 mL. The proportion of patients with Grade ≥2 GI toxicity with and without V(45) >150 mL was 65% vs. 33% (p = 0.03). Logistic model parameter estimates V50 and γ were 161 mL (95% confidence interval [CI] 60-399) and 0.31 (95% CI 0.04-0.63), respectively. On multivariable logistic regression, increased V(45) was associated with an increased odds of Grade ≥2 GI toxicity (odds ratio 2.19 per 100 mL, 95% CI 1.04-4.63, p = 0.04).
  
  
  CONCLUSIONS
  Our results support the hypothesis that increasing bowel V(45) is correlated with increased GI toxicity in cervical cancer patients undergoing IMRT and concurrent cisplatin. Reducing bowel V(45) could reduce the risk of Grade ≥2 GI toxicity by approximately 50% per 100 mL of bowel spared.
authors.affiliation: Center for Advanced Radiotherapy Technologies, Department of Radiation Oncology, University of California San Diego, La Jolla, CA, USA.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Simpson
authors.forename: William Y
authors.initials: WY
authors.lastname: Song
authors.forename: Vitali
authors.initials: V
authors.lastname: Moiseenko
authors.forename: Brent S
authors.initials: BS
authors.lastname: Rose
authors.forename: Catheryn M
authors.initials: CM
authors.lastname: Yashar
authors.forename: Arno J
authors.initials: AJ
authors.lastname: Mundt
authors.forename: Loren K
authors.initials: LK
authors.lastname: Mell
mesh_terms: D000970:Antineoplastic Agents / Q000009:adverse effects* / Q000627:therapeutic use; D059248:Chemoradiotherapy / Q000009:adverse effects*; D002945:Cisplatin / Q000009:adverse effects* / Q000627:therapeutic use; D005260:Female; D041981:Gastrointestinal Tract / Q000473:pathology / Q000528:radiation effects*; D006801:Humans; D008875:Middle Aged; D058958:Organs at Risk / Q000528:radiation effects; D011832:Radiation Injuries / Q000473:pathology*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects* / Q000379:methods; D012044:Regression Analysis; D012189:Retrospective Studies; D002583:Uterine Cervical Neoplasms / Q000473:pathology / Q000628:therapy*
chemical_list: D000970:Antineoplastic Agents; D002945:Cisplatin