¹⁸F-fluorodeoxyglucose positron emission tomography immediately after chemoradiotherapy predicts prognosis in patients with locoregional postoperative recurrent esophageal cancer

Objectives: The objectives of this study were to reveal the utility of ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) within 7 days after chemoradiotherapy to predict prognosis in patients with postoperative recurrent esophageal cancer. Materials and methods: Patients scheduled to undergo concurrent chemoradiotherapy for postoperative locoregional recurrence of esophageal cancer were recruited. Selection criteria were: (1) locoregional recurrence, (2) no previous radiation therapy, (3) planning treatment with concurrent chemoradiotherapy, (4) FDG-PET performed <2 weeks before chemoradiotherapy, and (5) no serious diabetes. FDG-PET was performed <7 days after chemoradiotherapy. No more treatment after chemoradiotherapy was given until disease progression was diagnosed according to the Response Evaluation Criteria in Solid Tumors (RECIST). Correlations of FDG-PET findings with cause-specific survival and local control rates were investigated prospectively. Results: Twenty patients were enrolled. Median observation period of patients who survived was 45.0 months. Median maximum standardized uptake value (SUV_max) after chemoradiotherapy was 2.4, and median SUV _max before chemoradiotherapy was 8.4. Cause-specific survival and local control rates were significantly better for patients with SUV _max ≤ 2.4 after chemoradiotherapy (log-rank test, P = 0.033 and 0.010, respectively). SUV_max before chemoradiotherapy tended to be correlated only with cause-specific survival rate (log-rank test, P = 0.076). Change in metabolic activity of FDG was significantly correlated with local control rate (log-rank test, P = 0.042). Conclusions: FDG-PET performed even <7 days after chemoradiotherapy predicts prognosis in patients with postoperative recurrent esophageal cancer.