Low rate of thoracic toxicity in palliative paraspinal single-fraction stereotactic body radiation therapy

BackgroundThere has been an increase in the utilization of single-fraction stereotactic body radiation therapy (SBRT) to treat thoracic structures, but there have been few reports describing toxicity outcomes with this treatment.MethodsWe evaluated 119 sites (114 patients) with no prior history of thoracic radiation were treated from 10/1/2003 to 10/27/2008 with single-fraction SBRT to thoracic structures. The median dose to the gross tumor volume was 2400 cGy (range 1800–2400 cGy), as was the median dose to the planning target volume (range 1600–2400 cGy). A detailed review of thoracic toxicities was performed to include pneumonitis or Grade 2 or higher esophageal and bronchial toxicity. In addition, we retrospectively contoured the esophagus and bronchus of 48 patients treated in 2004–2005, prior to the establishment of dose constraints to determine the range of doses that these structures received.ResultsOf the contoured patients, the median dose to the hottest 1 cc (D1cc) of the esophagus was 1250 cGy (range 158–2572 cGy). The median bronchial D1cc was 1101 cGy (range 260–2211 cGy). At a median follow-up of 11.6 months, there were seven Grade 2 or higher esophageal toxicities, including one Grade 3 and one Grade 4 toxicities. There were two bronchial toxicities, one Grade 2 and one Grade 3. There were no cases of pneumonitis.ConclusionsHigh-dose single-fraction SBRT is well tolerated to the thoracic region, with most patients tolerating high doses to central structures without significant toxicity.