Lymph node sampling in lung cancer: how should it be done?

Systematic lymph node dissection in radical operation for lung cancer is recognized as an operative procedure which is expected to improve local control. We investigate the most effective method of lymph node dissection or sampling.

A retrospectrive study was carried out on 1815 patients who underwent systematic lymph node dissection and complete resection. The lymphatic route of metastatis from each lobe was investigated by examining which nodes had the most likelihood of metastasis, or to find out which is the sentinel lymph node in the case of small sized tumor, suitable for the video assisted thoracic surgery (VATS) approach.

At N2 level, distribution of major metastases from each lobe are as follows: right upper lobe tumor, #3 - 12.3% (80/648) and/or #4 - 8% (52/648); right middle lobe tumor, #3 and/or #7 - 16.4% (13/79); right lower lobe tumor, #7 - 13.7% (52/380); left upper lobe tumor, #5 - 12.3% (60/489) and/or #6 - 6.7% (33/489); and left lower lobe tumor, #7 - 11.9% (26/219). Small sized tumor requires lymph node sampling upon staging, and the lymph node most likely to become the first metastasis, i.e. sentinel node, are as follows: regardless of the location of tumor, #12, #11, and/or #10 in N1 level, which means dissection or sampling within these locations of lymph nodes are prerequisite. In N2 level, #3 and/or #4 in right upper lobe tumor, #3 and/or #7 in right middle lobe tumor, #7 in right lower lobe tumor, #5 and/or #6 in left upper lobe tumor, and, #7 in left lower lobe tumor.

In clinical T1NO lung cancer, sentinel lymph node sampling should be done first, if the nodes are negative, complete mediastinal lymph node dissection might be omitted. On the other hand, if the sentinel nodes are positive for pathology, complete medistinal lymph node dissection is required for curative resection.