A novel classification of MUC1 expression is correlated with tumor differentiation and postoperative prognosis in non-small cell lung cancer

4541 Backgrounds. 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 detailed study to assess clinical significance, especially prognostic impact, of MUC1 expression in NSCLC. Materials and methods. A total of 62 patients with completely resected pathologic (p-) stage I-IIIA NSCLC were retrospectively reviewed. Histological sections cut from primary tumors were immunohistochemicaly 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 HP-group (high-grade polarized expression), the LP-group (low-grade polarized expression), or the D-group (depolarized expression). Results. Twenty-four (38.7%), 21 (33.9%) and 17 (27.4%) patients were classified as the HP-group, the LP-group and the D-group, respectively. HP-expression was exclusively seen in adenocarcinoma, mostly in well-differentiated adenocarcinoma. D-expression was correlated with progressive stage and lymph node metastasis. For all of NSCLC patients, postoperative 5-year survival rates of the HP-, LP-and D-group were 78.3%, 51.5% and 56.2%, respectively, showing a trend of a favorable prognosis in HP-group and a poor prognosis in D-group (p=0.134 by the log rank test and p=0.081 by the Wilcoxon test among the three groups); the p-values between HP-and D-group by the log rank test and the Wilcoxon test were 0.074 and 0.042, respectively. For adenocarcinoma patients, the difference between the three groups was enhanced. The 5-year survival rates of HP-, LP-and D-group were 78.3%, 51.4% and 40.0%, respectively, showing a significant difference among the three groups (p=0.039 by the log rank test and p=0.012 by the Wilcoxon test); the p-values between HP-and D-group by the log rank test and the Wilcoxon test were 0.015 and 0.006, respectively. Conclusions. A novel classification of MUC1 expression pattern (HP, LP and D) was correlated with tumor differentiation as well as postoperative survival in NSCLC, especially in lung adenocarcinoma.