Prediction of Occult Lymph Node Metastasis by Metabolic Parameters in Patients with Clinically N0 Esophageal Squamous Cell Carcinoma

UNLABELLED: The aim of this study was to investigate the value of (18)F-FDG parameters of the primary tumor in predicting occult lymph node metastasis in patients with clinically N0 esophageal squamous cell carcinoma. METHODS: The study comprised 143 consecutive patients (mean age ± SD, 63.9 ± 8.6 y; range, 31.8-81.2 y) from May 2003 to January 2010 who had clinically N0 esophageal squamous cell carcinoma based on preoperative imaging studies including chest CT, (18)F-FDG PET/CT, and endoscopic ultrasound. We measured maximum standardized uptake value (SUV max), mean SUV (SUV mean), total lesion glycolysis (TLG), and metabolic tumor volume (MTV) of the primary tumor and analyzed the relationship between clinicopathologic variables including PET parameters and occult lymph node metastasis using a logistic regression model. RESULTS: Univariate analysis indicated that clinical T classification, SUV max, SUV mean, MTV, TLG, and longitudinal diameter of tumor were significant risk factors associated with occult lymph node metastasis. Optimal thresholds were cT2-4, SUV max ≥ 4.8, SUV mean ≥ 3.2, MTV ≥ 5.5 cm(3), TLG ≥ 220, and diameter ≥ 3.8 cm. After multivariate analysis, the logistic regression model revealed that clinical T classification (hazard ratio [HR], 4.6; 95% confidence interval [CI], 1.7-12.4; P = 0.003) and SUV max (HR, 3.5; 95% CI, 1.3-9.2; P = 0.012) were independent risk factors. The combination of SUV max and clinical T classification (HR, 13.2; 95% CI, 5.4-31.9; P < 0.001) was a significantly better powerful risk factor for occult lymph node metastasis than SUV max or clinical T classification alone. Sensitivity, specificity, positive predictive value, and negative predictive value of the combination of clinical T classification and SUV max were 73.0%, 81.5%, 60.0%, and 89.7%, respectively. CONCLUSION: SUV max, combined with clinical T classification, may be useful for predicting occult lymph node metastasis in patients with clinically N0 squamous cell carcinoma of the esophagus.