Sentinel node mapping and micrometastasis in patients with clinical stage IA non-small cell lung cancer

Many evidences suggest that prognosis of non-small cell lung cancer (NSCLC) with lymph node micrometastases (LNMM) is poor compared with those without LNMM. Therefore, it is better to evaluate LNMM through immunohistochemistry (IHC) of serial sectioning of all dissected lymph nodes. However, this labor-intensive approach is impossible in a practical setting. Therefore, we examined whether we are able to efficiently diagnose LNMM using the sentinel node (SN) mapping. Fifty-one patients with clinical T1N0M0 NSCLC were enrolled in this study. SNs were then detected intraoperatively. After SN mapping, lobectomy and hilar and mediastinal lymph node dissection were performed. Metastases of all dissected lymph nodes were examined by hematoxylin and eosin (H&E) staining and immunohistochemical cytokeratin staining. SN detection rate was 80.4% (41/51). Average number of SNs was 1.8+/-1.1 in a patient. Lymph node metastases were diagnosed in two patients using H&E staining. LNMM were found only in SNs of two patients. On the other hand, micrometastasis was not found in non-SN. According to these results, two patients with clinical T1N0M0 NSCLC migrated to T1N1M0. Evaluation of micrometastases of all dissected lymph nodes may be substituted by evaluating micrometastases of SNs. We believe that further studies are warranted to determine the most useful clinical applications.