Purposes：To assess the independent predictor of lymph node metastasis（ LNM） in peripheral smallsized non-small cell lung cancers （NSCLCs）, we conducted a clinicopathologic analysis of patients with small-sized NSCLCs with and without intrathoracic LNM. Methods：We retrospectively studied 213 patients who had undergone surgical resection of NSCLCs 20 mm or less in diameter. Categories of patient characteristics were divided into 2 groups based on clinicopathologic features, and the incidence of LNM was compared. Univariate and multivariate analyses of factors affecting overall survival（ OS） were also conducted. Results：In pN1-2 group （n＝19）, the incidence of elevated （＞5 ng/dl） of preoperative carcinoembryonic antigen （CEA） and larger tumor size （＞10 mm） was significantly higher than that in pN0 group （n＝194） ［p＝0.0004, 0.0025］. Preoperatively, 73.7％ patients were diagnosed as having lower stage in N-staging. Multivariate analysis identified only pN staging as an independent prognostic factor （p＝0.002）. Conclusions：It is likely that preoperative CEA and tumor size are useful in selecting patients with micro-N1-2 disease among those with small-sized NSCLCs. Our results indicate that limited resection should be avoided in patients with elevated CEA or tumors more than 10 mm in size, even if preoperative radiographic findings suggest no intrathoracic LNM.
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