title: Predicting the risk of secondary lung malignancies associated with whole-breast radiation therapy.
abstract: OBJECTIVE
  The risk of secondary lung malignancy (SLM) is a significant concern for women treated with whole-breast radiation therapy after breast-conserving surgery for early-stage breast cancer. In this study, a biologically based secondary malignancy model was used to quantify the risk of secondary lung malignancies (SLMs) associated with several common methods of delivering whole-breast radiation therapy (RT).
  
  
  METHODS
  Both supine and prone computed tomography simulations of 15 women with early breast cancer were used to generate standard fractionated and hypofractionated whole-breast RT treatment plans for each patient. Dose-volume histograms (DVHs) of the ipsilateral breast and lung were calculated for each patient on each plan. A model of spontaneous and radiation-induced carcinogenesis was used to determine the relative risks of SLMs for the different treatment techniques.
  
  
  RESULTS
  A higher risk of SLMs was predicted for supine breast irradiation when compared with prone breast irradiation for both the standard fractionation and hypofractionation schedules (relative risk [RR] = 2.59, 95% confidence interval (CI) = 2.30-2.88, and RR = 2.68, 95% CI = 2.39-2.98, respectively). No difference in risk of SLMs was noted between standard fractionation and hypofractionation schedules in either the supine position (RR = 1.05, 95% CI = 0.97-1.14) or the prone position (RR = 1.01, 95% CI = 0.88-1.15).
  
  
  CONCLUSIONS
  Compared with supine whole-breast irradiation, prone breast irradiation is associated with a significantly lower predicted risk of secondary lung malignancy. In this modeling study, fractionation schedule did not have an impact on the risk of SLMs in women treated with whole-breast RT for early breast cancer.
authors.affiliation: Department of Radiation Oncology, Columbia University Medical Center, New York, NY 10032, USA. jon9024@nyp.org
authors.forename: John
authors.initials: J
authors.lastname: Ng
authors.forename: Igor
authors.initials: I
authors.lastname: Shuryak
authors.forename: Yanguang
authors.initials: Y
authors.lastname: Xu
authors.forename: K S
authors.initials: KS
authors.lastname: Clifford Chao
authors.forename: David J
authors.initials: DJ
authors.lastname: Brenner
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Burri
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000209:etiology*; D015412:Mastectomy, Segmental; D008875:Middle Aged; D008954:Models, Biological; D009381:Neoplasms, Radiation-Induced / Q000209:etiology*; D016609:Neoplasms, Second Primary / Q000209:etiology*; D056888:Patient Positioning; D016684:Prone Position; D011859:Radiography; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D018714:Radiotherapy, Adjuvant / Q000379:methods; D018570:Risk Assessment / Q000379:methods; D016683:Supine Position