Correlation between F-18 FDG PET/CT and EGFR mutations in lung adenocarcinoma

Objectives Although F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) has been proposed as a noninvasive surrogate for tumor biology in non-small cell lung cancer, conflicting results have been reported thus far. The purpose of this study was to determine whether the maximum standardized uptake value (SUVmax) and metabolic tumor volume (MTV) of the primary tumor on F-18 FDG PET/CT correlate with epidermal growth factor receptor (EGFR) mutation status.

Methods Lung adenocarcinoma patients who underwent EGFR mutation analysis and pretreatment F-18 FDG PET/CT scans were retrospectively identified. SUVmax was measured for the primary tumor and MTV was calculated by applying a threshold of SUV 2.5 (MTV2.5), 50%SUVmax (MTV50%), and background-level adjusted for liver (MTVliver). The association of EGFR mutation status with the SUVmax and various volumetric parameters of the primary tumor from the F-18 FDG PET/CT was evaluated.

Results Of the 208 patients included in this study, EGFR mutations were identified in 126 (61%). No statistically significant difference in SUVmax (p=0.275), MTV2.5 (p=0.278), MTV50% (p=0.943) and MTVliver (p=0.988) of the primary tumors between EGFR-mutant and wild-type lung adenocarcinoma patients was found. Logistic regression analysis also showed that none of the metabolic parameters were a statistically significant predictor of EGFR mutation status (p= 0.350, 0.689, 0.275 and 0.549, respectively) when stratified by their median values. Further analysis of the metabolic parameters with the EGFR-mutants stratified by specific tyrosine kinase exon genotype revealed no statistically significant findings.

Conclusions In this retrospective study, F-18 FDG-PET/CT parameters such as SUV and MTV did not correlate with EGFR mutation status. These results may account for why previous reports in the literature have contradicted each other. It is possible that F-18 FDG-PET/CT does not in fact provide useful information in discriminating patients who harbor EGFR mutations