Patterns-of-Care for Thoracic Stereotactic Body Radiotherapy among Practicing Radiation Oncologists in the United States

Introduction: Radiation oncologists were surveyed to assess practice patterns in the use of stereotactic body radiotherapy (SBRT) for lung cancer. Methods: A customized patterns-of-care survey, consisting of 18 questions and two clinical scenarios, was e-mailed to 136 academic radiation oncologists and 768 community practitioners to evaluate the technical basis and delivery parameters associated with SBRT. Results: A total of 117 surveys were evaluable. The cited delivery techniques included: static noncoplanar beams (48%), intensity-modulated radiotherapy (41%), rotational intensity-modulated radiotherapy (47%), dynamic conformal arcs (7%), and small-beam delivery with fiducial tracking (24%), with 46% using multiple techniques. The immobilization methods included: stereotactic frame (10%), alpha cradle or vacuum-lock system (52%), wingboard (3%), stereotactic frame with an alpha cradle or vacuum-lock system (11%); combination of devices (14%), or no immobilization (9%). Abdominal compression was used by 51% and respiratory gating by 31%. For a peripheral T1N0 tumor, the preferred doses included: 25 to 34 Gy in one fraction (1%); 54 to 60 Gy in three fractions (56%), 48 to 50 Gy in four fractions (18%), and 50 to 60 Gy in five fractions (25%). For a centrally located T1N0 tumor, 58% recommended SBRT outside a clinical protocol, with recommended doses ranging from 40 to 60 Gy in three to 10 fractions. The recommended interval to first surveillance imaging ranged from 6 weeks or lesser (32%) to 25 weeks or more (2%). Conclusions: Considerable variation exists for thoracic SBRT with regard to dose selection, fractionation, immobilization, planning, management of central lesions, and surveillance. Ongoing prospective evaluation is recommended to identify best practices and provide continual process improvement.