Can a thoracic surgeon identify lymph node metastases during surgery based on their size? Analysis of 844 metastatic and 10,462 nonmetastatic lymph nodes.

Objective: A metastatic lymph node commonly becomes enlarge; however, there is limited data available with regard to the direct measurement of lymph nodes and their clinicopathologic characteristics.

Methods: The size of dissected lymph node was quantified in a total of 848 nodes with metastasis and 10,462 nodes without metastasis from 454 patients with lung cancer who underwent a pulmonary resection with lymph node dissection.

Results: The short axis and the volume of the metastatic lymph nodes were significantly greater than those of the nonmetastatic ones. The smaller the lymph node, the less frequently the lymph nodes were metastatic; however, the ratios of nodes smaller than the fifth largest lymph node with metastasis of adenocarcinoma and squamous cell carcinoma were 21.8 to 26.2%, respectively. When the hilar and mediastinal lymph node stations were examined, 1.14 to 4.00% of the lung cancer patients had lymph node metastasis in small lymph node despite having no metastases in the largest and second largest lymph nodes.

Conclusions: The small lymph nodes in the hilar or mediastinal stations frequently had metastases of carcinoma even though largest and second largest lymph nodes were negative for metastases, especially in adenocarcinoma cases. Surgical oncologists should, therefore, perform systemic lymph node dissection, and not sampling, during a pulmonary resection of lung cancer.