title: Estimation of radiation-induced secondary cancer risks for early-stage non-small cell lung cancer patients after stereotactic body radiation therapy.
abstract: OBJECTIVE
  In this study, we evaluated radiation-induced secondary lung cancer risks for the lung and the breast from stereotactic body radiation therapy treatment of early-stage non-small cell lung cancer with different radiation therapy treatment modalities.
  
  
  METHODS
  Ten patients (5 men and 5 women) with early-stage non-small cell lung cancer who received definitive stereotactic body radiation therapy treatments were retrospectively selected. For each patient, two 3-dimensional conformal radiation therapy (3D-CRT) plans using 6- and 10-MV photons, respectively; a helical tomotherapy (HT) plan; and 2 volumetric modulated arc therapy (VMAT) plans using 1 and 2 arcs, respectively, were generated. The excess absolute risk (EAR) for secondary cancer occurrence was calculated using 3 organ equivalent dose models: the linear-exponential model, the plateau model, and the linear model for prescription dose range of 30 to 70 Gy.
  
  
  RESULTS
  The 3D-CRT plans showed significantly lower monitor units compared with the rotational intensity modulate radiation therapy plans. Based on each of the 3 organ equivalent dose models, HT and VMAT plans showed comparable average EARs to both the lung and the breast compared with the 3D-CRT plans in the prescription dose range of 30 to 70 Gy. At a prescription dose of 50 Gy and using the linear-exponential model, the average lung EAR estimation ranged from 15.7 ± 5.3 to 16.0 ± 6.5 per 10,000 patients per year with the 5 delivery techniques, and the average EAR estimation for the breast ranged from 18.0 ± 14.0 to 21.0 ± 15.0 per 10,000 patients per year. The secondary cancer risk increased approximately linearly with mean organ dose. The 3D-CRT plans showed significantly higher secondary cancer risk for the ipsilateral lung and lower risk for the contralateral lung compared with the HT and VMAT plans.
  
  
  CONCLUSIONS
  Rotational intensity modulate radiation therapy techniques including helical tomotherapy and VMAT do not increase secondary cancer risks for the lung or the breast compared with 3D-CRT techniques, despite higher monitor units used.
authors.affiliation: Department of Radiation Oncology, City of Hope National Medical Center, Duarte, California. Electronic address: chan@coh.org.
authors.forename: Chunhui
authors.initials: C
authors.lastname: Han
authors.affiliation: Department of Radiation Oncology, City of Hope National Medical Center, Duarte, California.
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Schultheiss
authors.affiliation: Department of Radiation Oncology, City of Hope National Medical Center, Duarte, California.
authors.forename: Jeffrey Y C
authors.initials: JYC
authors.lastname: Wong
mesh_terms: D001943:Breast Neoplasms / Q000209:etiology / Q000473:pathology; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D009381:Neoplasms, Radiation-Induced / Q000209:etiology*; D016634:Radiosurgery / Q000009:adverse effects* / Q000379:methods*; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000009:adverse effects / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods; D012189:Retrospective Studies