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 two groups: 181 with tumors ≤3cm and 95 with tumors >3cm to study their histopathologic and clinicopathologic characteristics. The long lepidic structure at the tumor margin was designated as the marginal lepidic feature. In the group with tumors ≤3cm, 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 >3cm, the lepidic component and marginal lepidic feature were not correlated with histopathologic or clinicopathologic characteristics. Furthermore, the patients with tumors ≤3cm and marginal lepidic lesions demonstrated significantly longer overall survival than 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.