Prognostic Impact of the Histologic Lepidic Component in Pathologic Stage IA Adenocarcinoma

Introduction: Because several articles have reported a prognostic association with the radiologic features of ground-glass opacity, we explored whether the histologic presence of a lepidic component had similar significance. Methods: We retrospectively evaluated 380 consecutive surgically resected lung adenocarcinomas (ADCs) of pathologic (p)stage IA. The tumors were classified into lepidic-positive and lepidic-negative ADCs. Clinicopathologic characteristics, radiographic ground-glass opacity status, and disease-free survival were compared between lepidic-positive and lepidic-negative ADCs and between part-solid and solid nodules on computed tomography images. Results: Of the 380 cases, 176 (46.3%) were lepidic-positive ADCs. Of the overall patients with pT1, lepidic-positive ADCs were found to have significantly better recurrence-free survival (5 y, 95.4% versus 87.0%, p = 0.005), but this significance was not reproduced in pT1 subcategories (pT1a, pT1b, and pT1c). Furthermore, the presence of the lepidic component was not an independent prognostic factor in the multivariate analysis (hazard ratio = 0.46 [95% confidence interval: 0.19–1.14], p = 0.09). We also analyzed the extent of the lepidic component with 10% incremental valuables. Although we found that a 10% or greater extent of lepidic component made the recurrence-free survival difference the largest, a clear prognostic impact was not obtained with this cutoff point. Conclusions: Although lepidic-positive ADCs tended to have a favorable outcome, the lepidic component was not a clear independent prognostic factor in pstage I ADC.