Clinical Significance of Subcellular Localization of Maspin in Patients with Pathological Stage IA Lung Adenocarcinoma

Background/aim Maspin is a tumor-suppressor protein and its prognostic value in lung adenocarcinoma has been reported. However, little is known about the clinical impact of subcellular localization of maspin in early-stage lung adenocarcinoma. We aimed to evaluate the clinical significance of subcellular localization of maspin in patients with pathological stage (p-stage) IA lung adenocarcinoma categorized by the new eighth edition TNM classification. Patients and methods We immunohistochemically analyzed 181 tissue samples from p-stage IA1 (n=37), IA2 (n=92) and IA3 (n=52) lung adenocarcinomas using antibody for maspin. Results The 181 cases fell into five predominant subtypes: lepidic (n=32), acinar (n=97), papillary (n=30), solid (n=20) and micropapillary (n=2). The frequencies of maspin staining were: cytoplasmic-only in 24.9%; pancellular (nuclear and cytoplasmic) in 8.8%; nuclear-only in 0.6%; no staining in 65.7%. Cytoplasmic-only staining significantly correlated with high pathological T-classification (p=0.039), lymphatic invasion (p=0.002) and poorer tumor differentiation (p=0.002). The patients were followed-up for 12-151 months (median=74 months), and the cytoplasmic-only staining significantly correlated with shorter disease-free survival (DFS) (p=0.034) and disease-specific survival (DSS) (p=0.036) by log-rank tests. In Cox's multivariate analysis, lymphatic invasion had the most significant effect on shorter DFS and DSS. Conclusion The expression of maspin in the cytoplasm alone could be useful for predicting unfavorable prognoses in patients with p-stage IA lung adenocarcinoma.