To compare 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) and computed tomography (CT) imaging characteristics in non-small cell lung cancer (NSCLC) with or without epidermal growth factor receptor (EGFR) mutations.
Methods. We retrospectively identified NSCLC patients who underwent EGFR mutation testing and pretreatment FDG-PET and CT scans. The maximum standard uptake value (SUVmax) of the primary tumor and any metastases was measured and normalized to the SUV of blood in the pulmonary artery. We compared normalized SUVmax values between EGFR-mutant and wild-type patients and modeled radiographic and clinical predictors of EGFR mutation status. Receiver operator characteristic (ROC) curves were used to identify potential SUV cutoffs predictive of genotype.
Results. We included 100 patients (24 EGFR-mutant and 76 wild-type). There was a trend for higher normalized SUVmax in the primary tumors among patients with EGFR-wild-type versus mutant (median, 3.4; range, 0.6–12.8; versus median, 2.9; range, 0.4–5.0; p = .09). Normalized SUVmax of nodal and distant metastases, and CT characteristics were not associated with genotype. On multivariate analysis, low normalized SUVmax of the primary tumor was predictive for EGFR mutation (odds ratio, 0.72; 95% confidence interval, 0.53–0.98; p = .034). ROC curve analyses yielded an area under the curve of 0.62, and identified a potential cutoff of 
5.0 to distinguish wild-type from mutant tumors.
Conclusions. In this retrospective study, high FDG avidity (normalized SUVmax 5) correlated with EGFR-wild-type genotype. Although genotyping remains the gold standard, further work to validate FDG-PET as a surrogate for tumor genotype may provide useful information in patients without available tumor tissue.
source: the oncologist
ARYAN'S BLOG 