title: Outcomes of stereotactic body radiotherapy (SBRT) treatment of multiple synchronous and recurrent lung nodules.
abstract: BACKGROUND
  Stereotactic body radiotherapy (SBRT) is evolving into a standard of care for unresectable lung nodules. Local control has been shown to be in excess of 90% at 3 years. However, some patients present with synchronous lung nodules in the ipsilateral or contralateral lobe or metasynchronous disease. In these cases, patients may receive multiple courses of lung SBRT or a single course for synchronous nodules. The toxicity of such treatment is currently unknown.
  
  
  METHODS
  Between 2006 and 2012, 63 subjects with 128 metasynchronous and synchronous lung nodules were treated at the Mayo Clinic with SBRT. Demographic patient data and dosimetric data regarding SBRT treatments were collected. Acute toxicity (defined as toxicity < 90 days) and late toxicity (defined as toxicity > = 90 days) were reported and graded as per standardized CTCAE 4.0 criteria. Local control, progression free survival and overall survival were also described.
  
  
  RESULTS
  The median age of patients treated was 73 years. Sixty five percent were primary or recurrent lung cancers with the remainder metastatic lung nodules of varying histologies. Of 63 patients, 18 had prior high dose external beam radiation to the mediastinum or chest. Dose and fractionation varied but the most common prescriptions were 48 Gy/4 fractions, 54 Gy/3 fractions, and 50 Gy/5 fractions. Only 6 patients demonstrated local recurrence. With a median follow up of 12.6 months, median SBRT specific overall survival and progression free survival were 35.7 months and 10.7 months respectively. Fifty one percent (32/63 patients) experienced acute toxicity, predominantly grade 1 and 2 fatigue. One patient developed acute grade 3 radiation pneumonitis at 75 days. Forty six percent (29/63 patients) developed late effects. Most were grade 1 dyspnea. There was one patient with grade 5 pneumonitis.
  
  
  CONCLUSIONS
  Multiple courses of SBRT and SBRT delivery after external beam radiotherapy appear to be feasible and safe. Most toxicity was grade 1 and 2 but the risk was approximately 50% for both acute and late effects.
authors.affiliation: Department of Radiation Oncology, University of Michigan, 1500 E Medical Drive, Ann Arbor, MI, 48105, USA. dawnowen@med.umich.edu.|Department of Radiation Oncology, Mayo Clinic Rochester, Rochester, MN, USA. dawnowen@med.umich.edu.
authors.forename: Dawn
authors.initials: D
authors.lastname: Owen
authors.affiliation: Department of Radiation Oncology, Mayo Clinic Rochester, Rochester, MN, USA. olivier.kenneth@mayo.edu.
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Olivier
authors.affiliation: Department of Radiation Oncology, Mayo Clinic Rochester, Rochester, MN, USA. mayo.charles@mayo.edu.
authors.forename: Charles S
authors.initials: CS
authors.lastname: Mayo
authors.affiliation: Department of Radiation Oncology, Mayo Clinic Rochester, Rochester, MN, USA. miller.robert@mayo.edu.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Miller
authors.affiliation: Department of Radiation Oncology, Mayo Clinic Rochester, Rochester, MN, USA. nelson.kathryn@mayo.edu.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Nelson
authors.affiliation: Department of Radiation Oncology, Mayo Clinic Rochester, Rochester, MN, USA. bauer.heather@mayo.edu.
authors.forename: Heather
authors.initials: H
authors.lastname: Bauer
authors.affiliation: Department of Radiation Oncology, MD Anderson Cancer Center, Houston, TX, USA. pdbrown@mdanderson.org.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Brown
authors.affiliation: Department of Radiation Oncology, Mayo Clinic Rochester, Rochester, MN, USA. park.sean@mayo.edu.
authors.forename: Sean S
authors.initials: SS
authors.lastname: Park
authors.affiliation: Department of Radiation Oncology, Mayo Clinic Rochester, Rochester, MN, USA. ma.daniel@mayo.edu.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Ma
authors.affiliation: Department of Radiation Oncology, Mayo Clinic Rochester, Rochester, MN, USA. garces.yolanda@mayo.edu.
authors.forename: Yolanda I
authors.initials: YI
authors.lastname: Garces
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000209:etiology*; D009367:Neoplasm Staging; D011379:Prognosis; D011446:Prospective Studies; D017564:Radiation Pneumonitis / Q000209:etiology*; D011874:Radiometry / Q000379:methods; D016634:Radiosurgery / Q000009:adverse effects*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D015996:Survival Rate; D055815:Young Adult