Comparison of changes in tumor metabolic activity and tumor size during chemotherapy of adenocarcinomas of the esophagogastric junction

We evaluated the temporal relationship between chemotherapy-induced changes in tumor glucose use and tumor size. Methods: Twenty patients with adenocarcinoma of the esophagogastric junction (AEG) were studied by ¹⁸F-FDG PET and CT scans before neoadjuvant chemotherapy, 14 d after the initiation of therapy, and 4 wk after the completion of therapy. Results: The relative change in ¹⁸F-FDG uptake was more than 2 times larger than the decrease in tumor size at all time points (P < 0.01). At 14 d after the initiation of chemotherapy, there was no correlation between the reduction in ¹⁸F-FDG uptake and tumor wall thickness. The change in ¹⁸F-FDG uptake after 14 d of therapy was significantly correlated with the reduction in tumor size after the completion of therapy. Conclusion: In AEG, changes in tumor metabolism are a more sensitive parameter for assessing the effects of chemotherapy than are changes in tumor size. Early changes in metabolic activity predict the subsequent reduction in tumor size.