Usefulness of sentinel lymph node biopsy for the detection of lymph node micrometastasis in early lung cancer

The purposes of this study were to examine the usefulness of the biopsy of the sentinel lymph nodes (SNs) for the accurate and effective detection of lymph node micrometastasis in early lung cancer and to clarify the spread of lymph node micrometastasis. One hundred and thirty-three c-stage IA non-small cell lung cancer patients in whom SNs could be identified by radioisotope (RI) method were enrolled. All dissected lymph nodes were stained with cytokeratin AE1/AE3 for the examination of micrometastasis. A total of 1375 lymph nodes including 220 SNs were dissected from the 133 patients. From the 220 SNs, 35 (15.9%) were found to be positive for metastasis. Of the other 185 SNs negative for metastasis, 19 (8.6%) were positive for micrometastasis. When patients were limited to those with pN0, there were no lymph nodes positive for micrometastasis other than SNs. In pN1-2 patients, micrometastasis to non-SNs were observed in 2.3-13.2%. In patients with pN0, micrometastasis was limited to SNs, and the results of the examination of SNs for micrometastasis accurately represented those of the examination of all lymph nodes. With advancement of the stage, micrometastasis was not limited to SNs and showed an irregular distribution.