Clinical implications of lymph node micrometastasis in patients with histologically node-negative (pNO) esophageal carcinoma

Background and Objectives: Lymph node micrometastasis is frequently detected in resected specimens of esophageal squamous cell carcinoma (ESCC). The goal of this study was to evaluate the clinical implication of micrometastasis in patients with lymph node-negative (pN0) disease. Methods: We examined the presence of micrometastasis in 2,511 lymph nodes from 53 patients with pN0 disease who underwent curative esophagectomy. All lymph nodes and the primary tumors were immunostained using an anticytokeratin antibody cocktail (AE1/AE3). Results: Micrometastasis was detected in 18 lymph nodes (0.72%) from 14 patients (26.4%). Detection of micrometastasis was not associated with the depth of invasion or the differentiation or lymphatic invasion. Lymph nodes containing micrometastases were widely distributed, but the most frequently involved nodes were located along the lesser curvature of the stomach. Four patients with micrometastasis (29%) and the only two patients without micrometastasis (5%) had recurrence as lymph node metastases (P=0.036). There were no significant differences in recurrence-free survival and disease-specific survival between patients with micrometastasis and patients without micrometastasis. Conclusions: These results show that micrometastasis might increase the risk of lymph node recurrence, but does not influence the survival of patients with pN0 ESCC.