Lepidic component at tumor margin: an independent prognostic factor in invasive lung adenocarcinoma.

Previous studies have proven that the lepidic component of lung adenocarcinoma is an independent prognostic factor and has a favorable effect on patient prognosis; however, no studies have reported the specific distribution of the lepidic component in lung cancer. In this study, we focused mainly on whether the lepidic component at the tumor margin was an independent prognostic factor for invasive lung adenocarcinoma. We reviewed 276 patients with invasive lung adenocarcinomas and divided them into 2 groups-181 with tumors of 3 cm or less and 95 with tumors of greater than 3 cm-to study their histopathologic and clinicopathological characteristics. The long lepidic structure at the tumor margin was designated as the marginal lepidic feature. In the group with tumors of 3 cm or less, the lepidic component and marginal lepidic feature were significantly associated with histologic subtype, TNM stage, and lymph node metastasis (P < .05), whereas in the group with tumors of greater than 3 cm, the lepidic component and marginal lepidic feature were not correlated with histopathologic or clinicopathological characteristics. Furthermore, the patients with tumors of 3 cm or less and marginal lepidic lesions demonstrated significantly longer overall survival than did those without the structure (P < .001). We concluded that the marginal lepidic feature of invasive lung adenocarcinoma is a significant histologic feature that suggests a better prognosis.