Diagnostic and Prognostic Value of 18F-FDG PET/CT for Patients with Suspected Recurrence from Squamous Cell Carcinoma of the Esophagus

Patients with esophageal squamous cell carcinoma (ESCC) are commonly at high risk of recurrence within 2 y after initial treatment. The aim of this study was to evaluate the role of 18F-FDG PET/CT in patients with possibly recurrent ESCC who underwent definitive treatment. Methods: Fifty-six patients with previously treated ESCC underwent PET/CT scans. The PET/CT findings were validated by histopathology or clinical follow-up of at least 6 mo. The sensitivity, specificity, and accuracy of PET/CT for detecting recurrence were calculated. Comparison of the standardized uptake value (SUV) was performed between patients grouped according to their status at the last follow-up (relapsed or relapse-free, alive or dead). The overall survival rates were estimated by the Kaplan–Meier method. The Cox proportional hazards model was used to evaluate independent prognostic variables for both univariate and multivariate survival analysis. Results: Forty-five (80.4%) patients had recurrence in 72 (66.1%) malignant sites. On PET/CT, there were 9 false-positive and 5 false-negative results. The overall sensitivity, specificity, and accuracy of PET/CT for detecting recurrence at all sites were 93.1% (67/72), 75.7% (28/37), and 87.2% (95/109), respectively. PET/CT was highly sensitive, specific, and accurate at regional and distant sites. At local sites, sensitivity was high, but specificity was lower (50%) because of a high incidence of false-positive findings. Patients who were confirmed with recurrence or who had died at the last follow-up had higher SUVs (P = 0.027 and <0.001, respectively). In multivariate survival analysis, therapeutic modality (hazard ratio = 0.437; P = 0.044), SUV (hazard ratio = 1.071; P = 0.029), and disease status on PET/CT (hazard ratio = 2.430; P = 0.045) were independent significant prognostic predictors for overall survival. The Kaplan–Meier survival curves indicated poor prognostic outcome in subgroup patients with higher SUVs or systemic disease on PET/CT. Conclusion: 18F-FDG PET/CT is highly effective for detecting recurrent ESCC. The relatively low specificity at local sites is associated primarily with a high rate of false-positive interpretations at anastomoses. PET/CT can also provide noninvasive and independent prognostic information using SUV and recurrent disease pattern on PET/CT images for previously treated ESCC.