Necrosis, as Identified on Pre-Radiotherapy 18F-FDG PET/CT, is a Predictor for Complete Metabolic Response in Patients with Non-Small Cell Lung Cancer.

Abstract Purpose: To investigate necrosis on pre-radiotherapy (RT) 18F-FDG PET/CT (PETNECROSİS) is a predictor for complete metabolic response (CMR) in patients with non-small cell lung cancer (NSCLC).Methods: We studied patients with inoperable stage I-III NSCLC who underwent pre- and post-radiotherapy 18F-FDG PET/CT. The relationship between CMR and PETNECROSIS, SUVmax, gross tumor volume calculated with 18F-FDG PET/CT (GTVPET-CT), tumor size, histology, metabolic tumor volume (MTV), and RT dose was assessed using logistic regression analysis. To evaluate necrosis on 18F FDG PET/CT, we drew a region of interest (ROI) in the area showing visually very low/or no fluorodeoxyglucose (FDG) uptake on PET images. If the SUVmax was lower than the blood pool SUVmax and showed significantly lower attenuation [10 to 30 Hounsfield Units (HU)] from the surrounding tissue on non-intravenous contrast-enhanced low dose correlative CT, we defined it as necrotic (PETNECROSİS).Results: Fifty-three patients were included in the study. The mean age was 68.1±9.8 years. Twenty-one patients had adenocarcinoma, 32 had squamous cell carcinoma. All parameters were independent of histologic status. Multivariate logistic regression analysis showed that, SUVmax ≤11.6vs>11.6 (p=0.003, OR:7.670, 95CI%:2.013-29.231) and PETNECROSİS absence/presence were independent predictors for CMR (p=0.028, OR:6.704, 95CI%1.214-30.394).Conclusion: The necrosis on 18F FDG PET/CT and SUVmax>11.6 could be an imaging marker for the complete metabolic response after chemoradiotherapy or RT alone in patients with NSCLC.