Prognostic Factors in Medically Inoperable Early Stage Lung Cancer Patients Treated with Stereotactic Ablative Radiation Therapy (SABR): Turkish Radiation Oncology Society Multicentric Study.

Objective We identified factors influencing outcomes in patients with medically inoperable early-stage lung cancer (MIESLC) treated with stereotactic ablative radiation therapy (SABR) at 14 centers in Turkey. Methods We retrospectively analyzed 431 patients with stage I-II MIESLC treated with SABR from 2009 through 2017. Age; sex; performance score; imaging technique; tumor histology and size; disease stage radiation dose, fraction, and biologically effective dose with an α/β ratio of 10 (BED10 ); tumor location; and treatment center were evaluated for associations with overall survival (OS), local control (LC), and toxicity. Results Median follow-up time was 27 months (range 1-115); median SABR dose was 54Gy (range 30-70) given in a median 3 fractions (range 1-10); median BED10 was151 Gy (range 48-180). Tumors were peripheral in 285 patients (66.1%), central in 69 (16%), and 100Gy (p=0.011), adenocarcinoma (p=0.025), and complete response on first evaluation (p=0.007) predicted favorable LC. BED10 >120Gy (hazard ratio [HR] 1.9, 95% confidence interval [CI] 1.1-3.2,p=0.019) and tumor size ( Conclusion SABR produced encouraging results, with satisfactory LC and OS and minimal toxicity. BED10 >120 Gy was needed for better LC and OS for large, non-adenocarcinoma tumors.