Medically inoperable early-stage lung cancer treated with stereotactic ablative radiation therapy (SABR): Multicenter study of Turkish radiation oncology group (TROG)

60th Annual Meeting of the American-Society-for-Radiation-Oncology (ASTRO) -- OCT 21-24, 2018 -- San Antonio, TXWOS: 000447811602068Purpose/Objective(s): To review treatment outcomes for SABR inmedically inoperable early stage lung cancer (NSCLC) patients treated byTurkish Radiation Oncology Group (TROG) member centers.Materials/Methods:Between 2009 and 2017, a total of 386 patients withNSCLC treated with SABR in 12 TROG centers. Patient, disease, andtreatment related prognostic factors were analyzed. Primary endpointswere, overall survival (OS), progression free survival (PFS), local control (LC) and regional control (RC) and radiation-related toxicities.Results:Median follow-up was 15 months. The median age at diagnosis was72 years (43-93) and 79% were men. Median tumor size was 30 mm (5- 78mm). Seventy-two percent of the patients have histologically confirmed diagnosiswhereas 28%of patientswere treated withclinical and radiologicalfindings only without pathological diagnosis. Staging was as follows; T1N0in 215, T2N0 in 166, T3N0 in 2 and T4N0 in 3 patients because of bilaterallytumors. Median SABR dose was 54Gy (30-70Gy), corresponding to a bio-logical equivalent dose (BED) of 112Gy (48- 180Gy) administered in me-dian5 (1-10) fractions.Responseevaluationwas made either with PET/CTorCTin median 3 months after SABR and complete response, partial response,stable disease and progression rates were 48%, 36%, 5.7% and 0.5%,respectively. The cumulative locoregional failure rate was 15%. Amongthese, 23 were local (6%) and 35 regional (9%) failures. Distant failure wasreported in 67 (17%) patients. One to 3 years LC and RC rates were 97%,91% and 93%, 86%, respectively. One and 3 years PFS and OS were 88%,72% and 90%, 65%, respectively. At their last follow up 271 patients (71%) were alive. Prognostic factors associated with LC, RC and OS were sum-marized in table 1. No severe acute side effects were observed. Overall 18patients experienced grade 3 pneumonitis, 11 patients had chest wall painand 1 patient had rib fracture.Conclusion:The results of this retrospective study have shown that SABRis a promising technique with satisfactory LC and OS rates and minimaltoxicity in patients with medically inoperabl NSCLC.American Society for Radiation Oncolog