We investigated whether the standardized uptake value (SUV) of the primary tumor, the tumor length measured on a PET image, the number of (18)F-FDG PET-positive nodes, and the PET stage were independent prognostic predictors over other clinical variables in patients with esophageal squamous cell carcinoma who were undergoing curative surgery.
Methods: Sixty-nine patients with newly diagnosed esophageal squamous cell carcinoma who underwent preoperative (18)F-FDG PET and curative esophagectomy were included. The events for survival analysis were defined as recurrence or metastasis and cancer-related death. The disease-free and overall survival rates of each variable were estimated by the Kaplan-Meier method. The Cox proportional hazards model was used to evaluate independent prognostic variables for multivariate survival analysis.
Results: Using univariate survival analysis, the presence of adjuvant therapy, pathologic stage, number of CT-positive nodes (0, 1, > or =2), tumor length on PET (cutoff: 3 cm, 5 cm), number of PET-positive nodes (0, 1, 2, > or =3), and PET stage (N0 M0, N1 M0, M1) were significant prognostic predictors for disease-free survival. However, only the number of PET-positive nodes was an independent significant prognostic predictor for disease-free survival in multivariate analysis (hazard ratio = 1.87, P < 0.001). In univariate survival analysis, the sex, presence of adjuvant therapy, clinical and pathologic stages, number of CT-positive nodes, maximum SUV of the primary tumor (cutoff: 6.3, 13.7), tumor length on PET, number of PET-positive nodes, and PET stage were significant prognostic predictors for overall survival. In contrast, the clinical stage (hazard ratio = 0.53, P < 0.05), pathologic stage (hazard ratio = 3.14, P < 0.005), tumor length by PET (hazard ratio = 2.74, P = 0.01), and number of PET-positive nodes (hazard ratio = 1.71, P < 0.05) were independent significant prognostic predictors for overall survival in multivariate analysis.
Conclusion: In addition to the pathologic stage, (18)F-FDG PET provides noninvasively independent prognostic information using the number of positive lymph nodes and the tumor length on the PET image in preoperative esophageal squamous cell carcinoma. A revised TNM classification system for esophageal carcinoma may consider tumor length and the number of positive lymph nodes as important prognostic factors.