title: Dosimetric analysis of radiation-induced gastric bleeding.
abstract: OBJECTIVE
  Radiation-induced gastric bleeding has been poorly understood. In this study, we described dosimetric predictors for gastric bleeding after fractionated radiation therapy.
  
  
  METHODS
  The records of 139 sequential patients treated with 3-dimensional conformal radiation therapy (3D-CRT) for intrahepatic malignancies were reviewed. Median follow-up was 7.4 months. The parameters of a Lyman normal tissue complication probability (NTCP) model for the occurrence of ≥grade 3 gastric bleed, adjusted for cirrhosis, were fitted to the data. The principle of maximum likelihood was used to estimate parameters for NTCP models.
  
  
  RESULTS
  Sixteen of 116 evaluable patients (14%) developed gastric bleeds at a median time of 4.0 months (mean, 6.5 months; range, 2.1-28.3 months) following completion of RT. The median and mean maximum doses to the stomach were 61 and 63 Gy (range, 46-86 Gy), respectively, after biocorrection of each part of the 3D dose distributions to equivalent 2-Gy daily fractions. The Lyman NTCP model with parameters adjusted for cirrhosis predicted gastric bleed. Best-fit Lyman NTCP model parameters were n=0.10 and m=0.21 and with TD₅₀ (normal) = 56 Gy and TD₅₀ (cirrhosis) = 22 Gy. The low n value is consistent with the importance of maximum dose; a lower TD₅₀ value for the cirrhosis patients points out their greater sensitivity.
  
  
  CONCLUSIONS
  This study demonstrates that the Lyman NTCP model has utility for predicting gastric bleeding and that the presence of cirrhosis greatly increases this risk. These findings should facilitate the design of future clinical trials involving high-dose upper abdominal radiation.
authors.affiliation: Department of Radiation Oncology, University of Michigan School of Medicine, Ann Arbor, Michigan 48109, USA. maryfeng@umich.edu
authors.forename: Mary
authors.initials: M
authors.lastname: Feng
authors.forename: Daniel
authors.initials: D
authors.lastname: Normolle
authors.forename: Charlie C
authors.initials: CC
authors.lastname: Pan
authors.forename: Laura A
authors.initials: LA
authors.lastname: Dawson
authors.forename: Sudha
authors.initials: S
authors.lastname: Amarnath
authors.forename: William D
authors.initials: WD
authors.lastname: Ensminger
authors.forename: Theodore S
authors.initials: TS
authors.lastname: Lawrence
authors.forename: Randall K
authors.initials: RK
authors.lastname: Ten Haken
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000532:radiotherapy; D018281:Cholangiocarcinoma / Q000532:radiotherapy; D015179:Colorectal Neoplasms / Q000473:pathology; D019583:Dose Fractionation, Radiation; D005260:Female; D006471:Gastrointestinal Hemorrhage / Q000209:etiology*; D006801:Humans; D016013:Likelihood Functions; D008103:Liver Cirrhosis / Q000150:complications; D008113:Liver Neoplasms / Q000532:radiotherapy* / Q000556:secondary; D008297:Male; D015233:Models, Statistical; D020266:Radiotherapy, Conformal / Q000009:adverse effects*; D012189:Retrospective Studies; D013270:Stomach / Q000528:radiation effects*; D013272:Stomach Diseases / Q000209:etiology*; D013997:Time Factors