Predicting lymph node metastasis for endoscopic resection of superficial esophageal squamous cell carcinoma

Objective: The aims of this study were to identify risk factors for lymph node metastasis and develop a reliable risk stratification system. Methods: Between May 2001 and December 2015, 262 patients who underwent endoscopic resection or surgery for superficial esophageal squamous cell carcinoma were enrolled. We evaluated possible predictive factors for lymph node metastasis: age, gender, tumor length, tumor area, circumferential spread, tumor location, gross appearance, depth of invasion, tumor differentiation, and lymphovascular invasion. Results: The incidence of lymph node metastasis was 14.5 % (38/262). In multivariate analysis, tumor size (>15 mm), depth of invasion (submucosal invasion), and lymphovascular invasion were significantly associated with lymph node metastasis. These factors were included in the risk stratification system and assigned scores; the total risk stratification system score was 0 to 6. The area under the receiver operating characteristic curve for predicting lymph node metastasis was 0.869 (95% confidence interval, 0.813-0.926). The high-risk group (risk stratification system score >= 3) exhibited a significantly higher risk of lymph node metastasis than the low-risk group (score <3) (26.5% vs 1.6%). There was no lymph node metastasis in patients with a risk stratification system of 0. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the risk stratification system were 94.7%, 55.4%, 26.5%, 98.4%, and 61.1%, respectively. Conclusions: We developed a risk stratification system that should facilitate the identification of patients with a high or low risk of lymph node metastasis. This may aid the precise selection of patients who can undergo endoscopic resection.