Prediction of the outcome of definitive chemoradiation by decrease in F-18 FDG uptake in nonsurgical esophageal squamous cell cancer.

Purpose: To analyze the predictive value of fluorine-18 fluorodeoxyglucose (F-18 FDG) uptake using positron emission tomography and computed tomography to assess the outcome of definitive chemoradiation in nonsurgical esophageal squamous cell carcinoma. Materials and Methods: A retrospective review of 61 patients with clinical stage T1-4, N0/1, and M0 was performed. Chemoradiation included chemotherapy with fluorouracil plus cisplatin and irradiation with a total dose of 5600 to 6400 centigray (cGy). Positron emission tomography combined with computed tomography scans were acquired before and during the therapy. The correlation between a decrease in FDG uptake and 5-year progression-free survival (PFS) was analyzed by a receiver operating characteristic curve method to determine a cutoff value. A 5-year overall survival (OS), PFS, and cancer-specific survival (CSS) were evaluated by Kaplan-Meier method. Results: The mean of standardized uptake value decreased significantly during chemoradiation (P = 0.001). Using 51% reduction of FDG uptake as a cutoff value provided a sensitivity of 76.9% and a specificity of 79.2% in predicting PFS (P = 0.000). The positive predictive value and negative predictive value were 50% and 95%, respectively. PFS, CSS, and OS were significantly different when grouped by this cutoff value (P < 0.05), and when dichotomized by stage T1-2 and T3-4 (P < 0.05), simultaneously with a decrease of 51% or more in FDG uptake. Conclusions: This study showed that a 51% decrease in FDG uptake during chemoradiation was a sensitive and accurate cut-point for predicting PFS. Stage T and decrease in FDG uptake were 2 independent predictive factors for 5-year PFS, CSS, and OS.