Prognostic significance of lepidic component in invasive non-mucinous adenocarcinoma of the lung

Although radiologic ground-glass opacity (GGO) components are associated with favorable prognosis, limited evidence supports the prognostic significance of corresponding histologic lepidic components. This study aimed to evaluate the prognostic value of lepidic components in patients with surgically resected invasive non-mucinous lung adenocarcinoma at pathologic (p-) stages I to IIIA.

We retrospectively analyzed 352 patients who underwent resection for invasive non-mucinous adenocarcinoma between 2012 and 2016. Histopathologic features, CT findings, clinical characteristics, and outcomes were reviewed. True non-invasive lepidic components were distinguished from invasive lepidic-like proliferations.

Lepidic-positive tumors (n = 226; 64 %) were significantly associated with female sex, presence and higher ratio of GGO, EGFR mutations, lower p-stage, and absence of pleural, vascular, and lymphatic invasion. The 5-year recurrence-free survival rate was significantly higher in lepidic-positive than lepidic-negative tumors (89 % vs. 47 %, p < 0.001). Multivariate analysis identified the presence of lepidic components as an independent predictor of favorable prognosis (hazard ratio, 0.48; CI, 0.29-0.81; p = 0.0057). A lepidic component ≥10 % was associated with favorable outcomes in p-stage IA and IB disease, regardless of exact percentage. Lepidic and GGO components showed a positive correlation and similar prognostic relevance.

Histologic lepidic and radiologic GGO components reflect less aggressive tumor behavior and may serve as favorable prognostic indicators in invasive non-mucinous lung adenocarcinoma.