title: Dosimetric parameters predictive of acute gastrointestinal toxicity in patients with anal carcinoma treated with concurrent chemotherapy and intensity-modulated radiation therapy.
abstract: OBJECTIVE
  To determine the dosimetric parameters predictive of acute gastrointestinal (GI) toxicity in anal cancer patients treated with intensity-modulated radiotherapy (IMRT) and concurrent chemotherapy.
  
  
  METHODS
  Fifty-eight anal cancer patients were treated with concurrent chemotherapy and IMRT. The bowel was delineated on the planning CT and included the intestinal cavity. Regression models with multiple independent predictors were used to test associations of clinical factors and dosimetric parameters with clinically significant GI toxicity (grade ≥3). Significant dosimetric factors were fitted to a normal tissue complication probability curve using a logit function and subsequently analyzed at multiple bowel volumes to determine the threshold for clinically significant GI toxicity.
  
  
  RESULTS
  Two patients (3.4%) experienced no acute GI toxicity, whereas 20 (34.5%) experienced grade 1 toxicity, 20 (34.5%) experienced grade 2, 16 (27.6%) experienced grade 3 and none experienced grade 4. Analysis showed that the volumes of bowel receiving 30 Gy (V30) and 40 Gy (V40) both correlated with clinically significant acute GI toxicity. In patients whose V30 was >310 cm(3), the rate of clinically significant acute GI toxicity was 38.9%, compared to 9.1% if V30 was ≤310 cm(3) (p = 0.016). If V40 was ≤70 cm(3), the rate of acute grade ≥3 toxicity was 6.3%, versus 35.7% if V40 was >70 cm(3) (p = 0.045).
  
  
  CONCLUSIONS
  This analysis demonstrates that the bowel dosimetric parameters are associated with clinically significant acute GI toxicity when IMRT is used in the management of anal cancer patients.
authors.affiliation: Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA.
authors.forename: S Gillianne
authors.initials: SG
authors.lastname: DeFoe
authors.forename: Peyman
authors.initials: P
authors.lastname: Kabolizadeh
authors.forename: Dwight E
authors.initials: DE
authors.lastname: Heron
authors.forename: Sushil
authors.initials: S
authors.lastname: Beriwal
mesh_terms: D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage / Q000627:therapeutic use*; D001005:Anus Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000532:radiotherapy*; D059248:Chemoradiotherapy / Q000009:adverse effects / Q000379:methods; D002945:Cisplatin / Q000008:administration & dosage / Q000009:adverse effects; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage / Q000009:adverse effects; D041981:Gastrointestinal Tract / Q000187:drug effects* / Q000473:pathology / Q000528:radiation effects*; D006801:Humans; D002955:Leucovorin / Q000008:administration & dosage / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D011832:Radiation Injuries / Q000209:etiology* / Q000473:pathology; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods; D012044:Regression Analysis
chemical_list: D002945:Cisplatin; D002955:Leucovorin; D005472:Fluorouracil