title: Dose-volume modeling of the risk of postoperative pulmonary complications among esophageal cancer patients treated with concurrent chemoradiotherapy followed by surgery.
abstract: OBJECTIVE
  The aim of this study was to investigate the effect of radiation dose distribution in the lung on the risk of postoperative pulmonary complications among esophageal cancer patients.
  
  
  METHODS
  We analyzed data from 110 patients with esophageal cancer treated with concurrent chemoradiotherapy followed by surgery at our institution from 1998 to 2003. The endpoint for analysis was postsurgical pneumonia or acute respiratory distress syndrome. Dose-volume histograms (DVHs) and dose-mass histograms (DMHs) for the whole lung were used to fit normal-tissue complication probability (NTCP) models, and the quality of fits were compared using bootstrap analysis.
  
  
  RESULTS
  Normal-tissue complication probability modeling identified that the risk of postoperative pulmonary complications was most significantly associated with small absolute volumes of lung spared from doses > or = 5 Gy (VS5), that is, exposed to doses < 5 Gy. However, bootstrap analysis found no significant difference between the quality of this model and fits based on other dosimetric parameters, including mean lung dose, effective dose, and relative volume of lung receiving > or = 5 Gy, probably because of correlations among these factors. The choice of DVH vs. DMH or the use of fractionation correction did not significantly affect the results of the NTCP modeling. The parameter values estimated for the Lyman NTCP model were as follows (with 95% confidence intervals in parentheses): n = 1.85 (0.04, infinity), m = 0.55 (0.22, 1.02), and D50 = 17.5 Gy (9.4 Gy, 102 Gy).
  
  
  CONCLUSIONS
  In this cohort of esophageal cancer patients, several dosimetric parameters including mean lung dose, effective dose, and absolute volume of lung receiving < 5 Gy provided similar descriptions of the risk of postoperative pulmonary complications as a function of the radiation dose distribution in the lung.
authors.affiliation: Department of Biostatistics and Applied Mathematics, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA. sltucker@mdanderson.org
authors.forename: Susan L
authors.initials: SL
authors.lastname: Tucker
authors.forename: H Helen
authors.initials: HH
authors.lastname: Liu
authors.forename: Shulian
authors.initials: S
authors.lastname: Wang
authors.forename: Xiong
authors.initials: X
authors.lastname: Wei
authors.forename: Zhongxing
authors.initials: Z
authors.lastname: Liao
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Komaki
authors.forename: James D
authors.initials: JD
authors.lastname: Cox
authors.forename: Radhe
authors.initials: R
authors.lastname: Mohan
mesh_terms: D000704:Analysis of Variance; D003131:Combined Modality Therapy; D016001:Confidence Intervals; D004938:Esophageal Neoplasms / Q000188:drug therapy / Q000532:radiotherapy* / Q000601:surgery*; D006801:Humans; D008168:Lung / Q000528:radiation effects*; D008954:Models, Biological; D011014:Pneumonia / Q000209:etiology*; D011183:Postoperative Complications / Q000209:etiology*; D011336:Probability; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal; D012128:Respiratory Distress Syndrome / Q000209:etiology*