18F-FDG PET in patients with esophageal squamous cell carcinoma undergoing curative surgery: prognostic implications

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.

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.

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.

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.