[The adequate diagnostic criterion of mediastinal lymph node size for detection of metastasis in primary lung cancer].

The size of lymph node is one of the most important factor in evaluation of lymph node metastasis in lung cancer. The most appropriate size for detecting lung cancer lymph node metastasis was studied by 2403 dissected lymph nodes in 75 operated cases of lung cancer. From the result of Receiver Operating Characteristic (ROC) curve analysis, long-axis diameter of the lymph node showed higher accuracy of diagnosis of metastasis than short-axis diameter. Metastasis of squamous cell carcinoma was diagnosed more accurately than that of adenocarcinoma. The most adequate threshold for detection of metastasis in squamous cell carcinoma was 10 mm in long-axis diameter with sensitivity of 73.8% and specificity of 78%. On the other hand, that of adenocarcinoma was 7 mm in long-axis diameter with sensitivity of 65.7% and specificity of 55.9%. That threshold value of adenocarcinoma was approximate to the value of normal lymph node size in the mediastinum. It was suggested that the size for detection of lymph node metastasis was depended upon histological type, and detection of lymph node metastasis in adenocarcinoma was extremely difficult.