Compare outcomes for biopsy-proven operable NSCLC treated with SBRT or standard of care lobectomy. Two hundred fifty-four patients with Stage I T1-2N0M0 NSCLC medically operable for resection underwent cone-beam CT image-guided SBRT to a median dose of 48 Gy/ 4 fractions (48-60 Gy; 3-5) (n = 32), 29/32 on a prospective clinical trial allowing patients refusing surgery (n = 32) OR Lobectomy (L) (n = 222) at a single institution. Median age was 73y for SBRT v 69 for L (P = 0.002). The following were similar between groups for SBRT vs L: median tumor size 2.2 vs 2.2 cm, median baseline max SUV 5.3 vs 6.0, gender 63% vs 59% female, T stage 75% vs 69% T1, synchronous lung cancer 6% vs 7%, smoking history 88% v 86%, and receipt of chemotherapy 9% v 16% (P = NS). SBRT group had more squamous cell ca (32% vs 5%, P<0.001), more prior lung cancer (25% v 1%, P<0.001), and lower PFT (median FEV1 1.4L vs 1.9L, %predFEV1 52% vs 79%, DLCO 10.6 vs 16.3, %pred DLCO 37% vs 72%, P<0.01). Mediastinoscopy was done in 19% of SBRT cases; all L cases had nodal staging. From these, a propensity match was performed using: age, gender, tumor size, prior/synchronous lung cancer, baseline SUV, and FEV1 yielding 14 pairs. Imbalanced factors remained %pred DLCO (46% vs 62%, P = 0.018), LN sampling (30% for SBRT) and histology. Survival/recurrence was calculated according to Kaplan Meier. Median follow-up time was 5.8 years for all cases. The 2-year, 3-year, and 5-year outcomes in Table 1. SBRT had higher rates of regional recurrence (RR), and clinical failure (CF). SBRT and L had similar local recurrence (LR) and distant metastasis (DM). L had higher overall survival (OS) and disease-free survival (DFS), with a P = 0.012 for cause-specific survival. For the matched group, SBRT had higher CF, lower DFS, and OS, with 5y LR (11% v 7%), RR 16% v 8%, and DM 21% v 15%. Baseline SUV, squamous histology, and metachronous ca predicted LR on UVA; all 3 remained significant on MVA (squamous histology HR 12.2). Significant factors predicting RR on UVA were squamous histology (P = 0.017, Hazard Ratio 6.1) and L v SBRT (P = 0.01, L HR 0.26) with the latter true on MVA. Tumor max dimension and baseline SUV were highly correlated and predicted DM, along with chemotherapy. SUV and chemo remained on MVA. SBRT in this operable population had similar rates of LR but higher rates of RR and CF and lower DFS and OS compared to lobectomy. Although operable, SBRT served as a second curative therapy for a new lung cancer in 25% of the applied population. Squamous histology serves as a predictor of not only LR but RR after SBRT, implying employment of more rigorous staging and further radiobiological evaluation.Tabled 1Abstract 36; Table 1All Cases2-year3-year5-yearP-valueSBRTLobectomySBRTLobectomySBRTLobectomyOverall Survival80%92%76%87%61%78%0.006Cause-Specific Survival90%96%90%94%77%91%0.123Local Recurrence3%2%8%3%8%5%0.388Regional Recurrence14%3%18%4%18%5%0.006Distant Metastasis7%8%11%10%11%12%0.909Clinical Failure18%10%22%13%40%16%0.006Disease-Free Survival73%87%69%81%53%72%0.018 Open table in a new tab