Long-term Results of RTOG 0236: A Phase II Trial of Stereotactic Body Radiation Therapy (SBRT) in the Treatment of Patients with Medically Inoperable Stage I Non-Small Cell Lung Cancer

training and validation sets (p < 0.0001). Overall survival in the validation set correlated closely with survival in the training set. Conclusions: This validated model demonstrates that operability, tumor diameter, PTV size, BED10 and age form the basis of a new risk stratification for OS in stage I NSCLC patients treated with SABR that may help define subgroups for future clinical trials. Author Disclosure: A.V. Louie: L. Funding Other; CARO-Elekta Research Fellowship, Royal College of Physicians and Surgeons of Canada Detweiler Travelling Fellowship, Resident Research Career Development Award University of Western Ontario. G. Rodrigues: None. C. Haasbeek: None. A. Warner: None. F.J. Lagerwaard: F. Honoraria; Varian Medical Systems. D.A. Palma: None. B.J. Slotman: E. Research Grant; Varian Medical Systems. F. Honoraria; Varian Medical Systems. G. Consultant; Varian Medical Systems. I. Travel Expenses; Varian Medical Systems. S. Senan: E. Research Grant; Varian Medical Systems. F. Honoraria; Varian Medical Systems. G. Consultant; Varian Medical Systems. I. Travel Expenses; Varian Medical Systems.