The Correlations between the Expression of Cyclin E and Clinical Features of the Primary Breast Cancer

ABSTRACT

PURPOSE: Cyclin E is a key regulatory protein in the G1-S transition during the cell cycle. The correlations between cyclin E protein and the clinical features of breast cancer were investigated in order to evaluate its clinical utility in invasive breast cancer. METHODS: An immunohistochemical assay for cyclin E was performed in 101 consecutive invasive breast cancers. The correlation between cyclin E expression and the clinicobiological parameters including patient survival was analyzed. RESULTS: Cyclin E expression was observed in 50 patients (49.5%). The scoring of the cyclin E expression level was divided into low (or=25%). In high nuclear grade tumors, cyclin E overexpression was much higher than that in low nuclear grade tumors (P=0.049). In the younger age group (<50 yrs), cyclin E expression was significantly higher than the older age group (P= 0.016). No significant correlation was observed between cyclin E and the tumor size, lymph node status, hormonal receptor status, histological grade, mitotic index and Ki67. In multivariate analysis, only the lymph node status was significantly associated with the patients' outcome (P= 0.002). CONCLUSION: Cyclin E overexpression did not have prognostic impact on the patients' survival rate in invasive breast cancer. In high nuclear grade tumors, the cyclin E expression level was much higher. The definite value of cyclin E as a clinicobiologic marker should be further investigated by prospective studies with other cell regulatory proteins.