Lung stereotactic body radiotherapy (SBRT): a single institution’s outcomes and methodology in the context of a literature review

Lung cancer is the leading cause of cancer death in the United States and worldwide, representing 13-14% of new cancers but 26-28% of deaths from cancer in the US in 2015 (1). Approximately 75% of lung cancer is non-small cell histology (NSCLC), of which up to 25% of patients present with early stage disease. Despite lung cancer afflicting mostly elderly patients, stage I-II NSCLC still portends as little as 5-10% overall survival (OS) at 5 years, compared to 50-80% 5-year OS with therapy. The standard of care for early stage lung cancer has historically been surgical resection due to a randomized clinical trial from the 1960s in which surgery improved OS compared to radiotherapy (RT) (2). RT has since then been reserved for patients who are medically inoperable or decline an invasive procedure, which is usually due to risk of complications. Primary RT in this setting using 3-dimensional conformal techniques (3D-CRT) has continued to show suboptimal results, with 3-year local control of 30-50% and 5-year OS of 15-30% (3-6), largely because dose escalation in conventionally fractionated RT is limited by surrounding normal tissue toxicity