title: Safety and Tolerability of SBRT after High-Dose External Beam Radiation to the Lung.
abstract: OBJECTIVE
  Stereotactic body radiotherapy (SBRT) is commonly used to treat unresectable lung nodules. Given its relative safety and effective local control, SBRT has also been used to treat recurrent lung nodules after high-dose external beam radiation (EBRT) to the lung. The toxicity of such treatment is unknown.
  
  
  METHODS
  Between 2006 and 2012, 18 subjects at the Mayo Clinic with 27 recurrent lung nodules were treated with SBRT after receiving EBRT to the lung. Median local control, overall survival, and progression-free survival (PFS) were described. Acute toxicity and late toxicity (defined as toxicity ≥ and >90 days, respectively) were reported and graded as per standardized CTCAE 4.0 criteria.
  
  
  RESULTS
  The median age of patients treated was 68 years. Fifteen patients had recurrent lung cancer as their primary histology. Twelve patients received ≥60 Gy of conventional EBRT prior to SBRT. SBRT dose and fractionation varied; the most common prescriptions were 48 Gy/4, 54 Gy/3, and 50 Gy/5 fractions. Only four patients had SBRT planning target volumes (PTVs) that overlapped more than 50% of their prior EBRT PTV. Two patients developed local recurrence following SBRT. With a median follow up of 21.2 months, median SBRT-specific overall survival and PFS were 21.7 and 12.3 months, respectively. No grade ≥3 acute or late toxicities were noted.
  
  
  CONCLUSIONS
  Stereotactic body radiotherapy may be a good salvage option for select patients with recurrent lung nodules following definitive EBRT to the chest. Toxicity is minimal and local control is excellent.
authors: Department of Radiation Oncology, Mayo Clinic Rochester , Rochester, MN , USA ; Department of Radiation Oncology, University of Michigan , Ann Arbor, MI , USA.
authors: Dawn
authors: D
authors: Owen
authors: Department of Radiation Oncology, Mayo Clinic Rochester , Rochester, MN , USA.
authors: Kenneth R
authors: KR
authors: Olivier
authors: Department of Radiation Oncology, Mayo Clinic Rochester , Rochester, MN , USA.
authors: Limin
authors: L
authors: Song
authors: Department of Radiation Oncology, Mayo Clinic Rochester , Rochester, MN , USA.
authors: Charles S
authors: CS
authors: Mayo
authors: Department of Radiation Oncology, Mayo Clinic Rochester , Rochester, MN , USA.
authors: Robert C
authors: RC
authors: Miller
authors: Department of Radiation Oncology, Mayo Clinic Rochester , Rochester, MN , USA.
authors: Kathryn
authors: K
authors: Nelson
authors: Department of Radiation Oncology, Mayo Clinic Rochester , Rochester, MN , USA.
authors: Heather
authors: H
authors: Bauer
authors: MD Anderson Cancer Center , Houston, TX , USA.
authors: Paul D
authors: PD
authors: Brown
authors: Department of Radiation Oncology, Mayo Clinic Rochester , Rochester, MN , USA.
authors: Sean S
authors: SS
authors: Park
authors: Department of Radiation Oncology, Mayo Clinic Rochester , Rochester, MN , USA.
authors: Daniel J
authors: DJ
authors: Ma
authors: Department of Radiation Oncology, Mayo Clinic Rochester , Rochester, MN , USA.
authors: Yolanda I
authors: YI
authors: Garces
keywords: acute; external beam radiotherapy; late toxicity; lung cancer; reirradiation; stereotactic body radiotherapy; toxicity tests
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