A Novel Classification of MUC1 Expression Is Correlated with Tumor Differentiation and Postoperative Prognosis in Non–Small Cell Lung Cancer

Background:MUC1 is a transmembrane mucin that plays an important role in tumor progression. Many clinical studies have suggested that the expression pattern of MUC1 core protein can be a useful prognostic marker in various malignancies, but the prognostic significance in non–small cell lung cancer (NSCLC) remains uncertain. We performed a study to assess clinical significance, especially prognostic impact, of MUC1 expression in NSCLC.Methods:A total of 62 patients with completely resected pathologic stage I to IIIA NSCLC were retrospectively reviewed. Histologic sections cut from primary tumors were immunohistochemically stained with an anti-MUC1 monoclonal antibody (CA15-3, clone DF3), which recognizes unglycosylated epitope of MUC1 core protein. According to MUC1 expression pattern, each patient was classified into the high-grade polarized expression (HP), the low-grade polarized expression (LP), or the depolarized expression (D) group.Results:Twenty-four (38.7%), 21 (33.9%), and 17 (27.4%) patients were classified into the HP group, the LP group, and the D group, respectively. HP was exclusively seen in adenocarcinoma, mostly in well-differentiated adenocarcinoma. D was correlated with progressive stage and lymph node metastasis. Postoperative survival of the D group seemed to be poorer than that of the HP group for all NSCLC patients, and the difference was enhanced in adenocarcinoma patients.Conclusion:A novel classification of MUC1 expression pattern (HP, LP, and D) was correlated with tumor differentiation and postoperative survival in NSCLC, especially in lung adenocarcinoma.