Size analysis of lymph node metastasis in esophageal cancer: Diameter distribution and assessment of accuracy of preoperative diagnosis

Background. In esophageal cancer, lymphatic spread occurs more frequently and at an earlier stage than in other gastrointestinal cancers, and both preoperative and intraoperative diagnoses of lymph nodes metastases are sometimes incorrect. Our objective was to measure the sizes of lymphatic metastases and to examine the accuracy of clinical diagnosis of lymphatic spread in patients with squamous cell carcinoma of the esophagus. Methods. The sizes of 320 metastatic lymph nodes of 9254 dissected nodes from 92 consecutive esophagectomy patients over 1 year were measured and compared with the sizes of the actual metastases within the nodes. These data allowed investigation of the correct rate of preoperative diagnosis of lymph node metastasis. Results. The mean diameter of the metastases was 4.8 mm, which was significantly smaller than that of the involved lymph nodes. Among the metastatic lymph nodes, 37.2% were less than 5 mm in diameter, and 63.1% of the metastases were less than 5 mm in diameter. The true-positive and true-negative diagnosis rate for all lymph node stations in three fields (neck, thorax, and abdomen) was only 23.2%, and the false-negative rate for diagnosis of lymph node metastasis was 53.7%. Conclusions. Two-thirds of involved lymph nodes had very small metastases (<5 mm), suggesting that limited confidence should be placed in the preoperative diagnosis of lymphatic spread. Therefore, extensive lymph node dissection appears appropriate in esophageal cancer surgery, given the small sizes of many metastases and the difficulty with preoperative diagnosis. © 2006 Japan Esophageal Society and Springer-Verlag.