Prognostic Significance of Solid and Micropapillary Components in Invasive Lung Adenocarcinomas Measuring ≤3 cm

We aimed to analyze the clinical impact of solid and micropapillary components in a series of Japanese patients resected for ≤3 cm lung adenocarcinoma. A total of 115 patients with ≤3 cm lung adenocarcinomas were reviewed and classified according to the American Thoracic Society and the European Respiratory Society classification. The presence of solid (S+) or micropapillary component (MP+) was defined when the component constituted ≥1% of the entire tumor. The impact of these components on disease-free (DFS) and disease-specific (DSS) survival was analyzed. Thirty (26.1%) cases with S+ and 27 (23.5%) with MP+ were identified, and multivariate analysis indicated that S+ status significantly reduced the duration of DFS and DSS. In 86 patients of acinar- and papillary-predominant subgroups, S+ and/or MP+ had the most significant effect on DFS and DSS by multivariate analysis. S+ and/or MP+ status predict worse prognosis in patients with acinar- and papillary-predominant lung adenocarcinoma.