Histologic patterns and molecular characteristics of lung adenocarcinoma associated with clinical outcome

Abstract

BACKGROUND: Lung adenocarcinoma is histologically heterogeneous and has 5 distinct histologic growth patterns: lepidic, acinar, papillary, micropapillary, and solid. To date, there is no consensus regarding the clinical utility of these patterns. METHODS: The authors performed a detailed semiquantitative assessment of histologic patterns of 240 lung adenocarcinomas and determined the association with patients' clinicopathologic features, including recurrence-free survival (RFS) and overall survival (OS) rates. In a subset of tumors, expression levels of 2 prognostic molecular markers were evaluated: thyroid transcription factor-1 (TTF-1) (n = 218) and a panel of 5 proteins (referred as the FILM signature index) (n = 185). RESULTS: Four mutually exclusive tumor histology pattern groups were identified: 1) any solid (38%), 2) any papillary but no solid (14%), 3) lepidic and acinar but no solid or papillary (30%), and 4) acinar only (18%). Patients in group 3 had a higher RFS rate than patients in group 1 (hazard ratio [HR], 0.4510; P =.0165) and group 2 (HR, 0.4253; P =.0425). Solid pattern tumors (group 1) were associated with a lower OS rate than nonsolid pattern tumors (all stages: HR; 1.665; P =.0144; stages I and II: HR, 2.157; P =.008). In the patients who had tumors with a nonsolid pattern, high TTF-1 expression was associated significantly with higher RFS (HR, 0.994; P =.0017) and OS (HR, 0.996; P =.0276) rates in all stages, and a high FILM signature index score was associated with lower RFS and OS rates in all stages (RFS: HR, 1.343; P =.0192; OS: HR, 1.371; P =.0156) and in stages I and II (RFS: HR, 1.419; P =.0095; OS: HR, 1.315; P =.0422). CONCLUSIONS: The presence of a solid histologic pattern was identified as a marker of unfavorable prognosis in patients with primary lung adenocarcinoma. High TTF-1 expression and low FILM signature index scores were associated with a better prognosis for patients who had tumors with a nonsolid pattern. Copyright © 2011 American Cancer Society.