Inoperable Early-Stage Non–Small-Cell Lung Cancer: Stereotactic Ablative Radiotherapy and Rationale for Systemic Therapy

Stereotactic ablative radiotherapy (SABR) is the standard treatment for medically inoperable, early-stage non–small-cell lung cancer. SABR results in high rates of in-field tumor control, but among larger and more biologically aggressive tumors, regional and distant failures are problematic. Cytotoxic chemotherapy is rarely used in this patient population and the benefit is unclear. Alternative systemic therapy options with a milder side-effect profile are of considerable interest, and several randomized phase III trials are currently testing immune checkpoint inhibitors in this setting. We review the rationale, data, and ongoing studies evaluating systemic therapy in medically inoperable, early-stage non–small-cell lung cancer treated with SABR.