Enhancer of Zeste Homologue 2 Expression in Breast Carcinoma Smears in Relationship with p53, Ki-67 and Other Prognostic Parameters

BACKGROUND: The polycomb group protein enhancer of zeste homologue 2 (EZH 2) has been reported as a marker of aggressive breast cancer. The aim of this study was to investigate the correlation between the expression of EZH 2 with p53 and Ki-67 expression and other clinicopathological parameters in primary breast carcinomas in order to determine the role of the above marker as a prognosticator of tumor aggressiveness and patient outcome. PATIENTS AND METHODS: One hundred primary operable breast cancer patients were investigated in order to identify the expression of EZH 2, Ki-67 and p53 in imprint smears immunocytochemically. The prevalence of expression of these markers was then correlated with clinicopathological parameters. Follow-up was available for all patients. RESULTS: EZH 2 was expressed in 64% of the cases and correlated with higher levels of p53 (relative risk = 3.00, p < 0.0001) and Ki-67 (relative risk = 3.25, p < 0.0001). Malignant cells showed immunoreactivity for all markers in the nucleus. Univariate analysis revealed a strong association between EZH 2 protein expression and tumor grade and size, lymph node metastasis, and HER-2 and estrogen and progesterone receptor status. Multivariable statistical analysis revealed that lymph node metastasis was the main predictor for EZH 2 expression. Decreased patient survival was also significantly associated with EZH 2 expression (p < 0.0001). CONCLUSIONS: EZH 2 expression may be a marker of poor prognosis in breast carcinoma patients and has been suggested as a candidate for targeted therapy.