title: Heart irradiation as a risk factor for radiation pneumonitis.
abstract: OBJECTIVE
  to investigate the potential role of incidental heart irradiation on the risk of radiation pneumonitis (RP) for patients receiving definitive radiation therapy for non-small-cell lung cancer (NSCLC).
  
  
  METHODS
  two hundred and nine patient datasets were available for this study. Heart and lung dose-volume parameters were extracted for modeling, based on Monte Carlo-based heterogeneity corrected dose distributions. Clinical variables tested included age, gender, chemotherapy, pre-treatment weight-loss, performance status, and smoking history. The risk of RP was modeled using logistic regression.
  
  
  RESULTS
  the most significant univariate variables were heart related, such as heart heart V65 (percent volume receiving at least 65 Gy) (Spearman Rs = 0.245, p < 0.001). The best-performing logistic regression model included heart D10 (minimum dose to the hottest 10% of the heart), lung D35, and maximum lung dose (Spearman Rs = 0.268, p < 0.0001). When classified by predicted risk, the RP incidence ratio between the most and least risky 1/3 of treatments was 4.8. The improvement in risk modeling using lung and heart variables was better than using lung variables alone.
  
  
  CONCLUSIONS
  these results suggest a previously unsuspected role of heart irradiation in many cases of RP.
authors.affiliation: Department of Radiation Oncology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110-1093, USA.
authors.forename: Ellen X
authors.initials: EX
authors.lastname: Huang
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Hope
authors.forename: Patricia E
authors.initials: PE
authors.lastname: Lindsay
authors.forename: Marco
authors.initials: M
authors.lastname: Trovo
authors.forename: Issam
authors.initials: I
authors.lastname: El Naqa
authors.forename: Joseph O
authors.initials: JO
authors.lastname: Deasy
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Bradley
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D002289:Carcinoma, Non-Small-Cell Lung / Q000532:radiotherapy*; D005260:Female; D006321:Heart / Q000528:radiation effects*; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008175:Lung Neoplasms / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009010:Monte Carlo Method; D011014:Pneumonia / Q000209:etiology*; D011832:Radiation Injuries / Q000150:complications* / Q000209:etiology; D011874:Radiometry; D012307:Risk Factors; D012720:Severity of Illness Index