Mediastinal nodal involvement in patients with clinical Stage I non-small-cell lung cancer: possibility of rational lymph node dissection

Background: The aim of this study is to elucidate the optimal candidate of selective lymph node dissection (LND) that reduces the extent of mediastinal LND according to clinical information including radiological evaluation in primary non-small-cell lung cancer (NSCLC) patients. Methods: Eight hundred and seventy-six patients with clinical(c)-stage I NSCLC (adenocarcinoma and squamous cell carcinoma), who underwent complete surgical resection between January 2003 and December 2009 were included in this study. We elucidated the lymph node metastatic incidence and distribution according to the primary tumor lobe location and extracted the associated clinicopathological factors, especially thin-section computed tomographic findings, with mediastinal lymph node involvement. Results: The total incidence of mediastinal lymph node metastasis was 9.1%. There were no cases with hilar and mediastinal lymph node metastasis in ground glass opacity-predominant tumors. There was no significant association of clinical factors with subcarinal lymph node metastasis in right upper-lobe and left upper-division adenocarcinoma. An elevated preoperative serum carcinoembryonic antigen level (p < 0.001) showed significant associations with upper mediastinal lymph node metastasis in the patients with bilateral lower-lobe primary lung adenocarcinoma. Conclusions: It would be acceptable to perform selective LND in patients with c-stage I NSCLC with ground glass opacity- predominant tumor. Elevated serum carcinoembryonic antigen was associated with upper mediastinal lymph node involvement in lower-lobe primary lung adenocarcinoma with radiologically solid-predominant tumor. We should be careful when applying selective LND to patients with solid-predominant tumor, especially located in the lower lobe.