18F-FDG PET as a Surrogate Biomarker in Non Small Cell Lung Cancer Treated with Erlotinib: Newly Identified Lesions Are More Informative Than Standardized Uptake Value

This study assesses the predictive value of F-18-FDG PET for overall survival in lung cancer patients treated with a targeted drug. Methods: F-18-FDG PET was performed in 125 second- or third-line non-small cell lung cancer (NSCLC) patients with a baseline Eastern Cooperative Oncology Group performance status less than 3 before treatment with erlotinib (150 mg daily) and 2 wk into treatment. The predictive value of F-18-FDG PET, clinical parameters, and epithelial growth factor receptor (EGFR) mutation status for survival duration was evaluated by fitting accelerated failure time models. Results: New lesions on PET at 2 wk, EGFR mutation status, performance status, and baseline tumor burden were independent and significant predictors of overall survival. Reduction of maximum standardized uptake value by at least 35% was predictive of survival only when EGFR mutation status was not accounted for. Conclusion: F-18-FDG PET in second- or third-line NSCLC patients at 2 wk after starting treatment with erlotinib carries information about overall survival. Parametric survival modeling enables a quantitative assessment of the predictive value of F-18-FDG PET in the context of clinical and laboratory information. New-lesion status by F-18-FDG PET at 2 wk is a potential surrogate biomarker for survival in NSCLC.