Stereotactic body radiotherapy (SBRT) for non-small cell lung cancer (NSCLC): Is FDG-PET a predictor of outcome?

Background and purpose: Distant metastases are the dominant mode of failure after stereotactic body radiotherapy (SBRT) for early-stage non-small cell lung cancer (NSCLC). The primary study objective was to evaluate if the maximum standardized uptake value (SUVmax) on pre-treatment FDG-PET/CT predicted clinical outcomes. Secondary objectives were to correlate 3-month post-SBRT SUVmax and change in SUVmax with outcomes. Materials and methods: Consecutive patients with medically inoperable early-stage NSCLG and an FDG-PET/CT scan before (n = 82) and 3 months after (n = 62) SBRT. Results: Median follow up was 2 years. On univariate analysis baseline SUVmax predicted for distant failure (p = 0.0096), relapse free survival (RFS) (p = 0.037) and local failure (p = 0.044). On multivariate analysis baseline SUVmax predicted for RFS (p = 0.037). Baseline SUVmax of above 5 was the most statistically significant cut off point for predicting distant failure (p = 0.0002). Baseline SUVmax >= 4.75 (median) was correlated with a higher risk of distant failure (p = 0.012) and poorer RFS (p = 0.04). Patients with a post-SBRT SUVmax >= 2 and a reduction of <2.55 had a significantly higher rate of distant failure. Conclusions: Pre-SBRT SUVmax on FDG-PET/CT correlated most strongly with distant failure. A cut off of >= 5 was the most significant. Post-SBRT SUVmax >= 2 and a reduction of <2.55 were associated with a higher risk of distant failure. (C) 2012 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 104 (2012) 62-66