The predictive value of 18F-FDG-PET early evaluation in patients with metastatic gastric adenocarcinoma treated with chemotherapy plus cetuximab

BACKGROUND: The aim of the study was to evaluate whether the therapy-induced reduction of the (18)F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) maximum standardized uptake value in patients with advanced gastric adenocarcinoma treated with chemotherapy plus cetuximab could predict the objective response and outcome early during the treatment. METHODS: The study was performed as a part of a phase II trial evaluating cetuximab plus the leucovorin/5-fluorouracil/irinotecan (FOLFIRI) regimen. The objective response was evaluated according to the response evaluation criteria in solid tumors (RECIST) every 6 weeks. The early metabolic response evaluated by 18F-FDG-PET was assessed according to our own evaluated cutoff value (<35%) after receiver operating characteristic (ROC) analysis. RESULTS: Twenty of 22 patients had positive baseline 18F-FDG-PET. The best RECIST response was: complete response (CR), 3; partial response (PR), 9; stable disease (SD), 8. Twelve patients (60%) were classified as metabolic responders and 8 (40%) as nonresponders. At the median follow-up time of 11 months, median time to disease progression (TTP) and overall survival (OS) for early metabolic responders versus nonresponders were 11 versus 5 months (P = 0.0016) and 16 versus 6 months (P = 0.1493), respectively. CONCLUSION: The early metabolic response evaluated by 18F-FDG-PET predicted the clinical outcome in this series of patients with advanced gastric cancer treated with chemotherapy plus cetuximab.