Clinicopathological significance of the proliferation markers Ki67, RacGAP1, and topoisomerase 2 alpha in breast cancer

Abstract

Objectives. The aims of this study are to evaluate expressions of Ki67, RacGAP1 (MgcRacGAP) and topoisomerase 2 alpha (TOP2a), the markers related with cell proliferation that have been proposed to affect the prognosis in the literature and correlate the results with clinicopathological parameters of breast cancer patients. Methods. Ki67, RacGAP1, and TOP2a antibodies were applied immunohistochemically to the tissue micrarray blocks of 457 female breast cancer patients. The results were correlated with clinical, prognostic, histopathological features, and other immunohistochemical findings (estrogen receptor [ER], progesterone receptor [PR], HER2, cytokeratin [CK]5/6, CK14, epidermal growth factor receptor [EGFR] and vimentin), statistically. Results. Ki67 expression demonstrated direct correlation with TOP2a expression, mitotic count, tumor grade, geographic necrosis, basal-like phenotype. RacGAP1 expression was directly correlated with TOP2a expression, nipple invasion, and number of metastatic lymph nodes, and it was inversely correlated with PR expression. TOP2a expression was directly correlated with vimentin and Ki67 expressions, mitotic count, tumor grade, and geographic necrosis, and nipple invasion, and negatively correlated with ER and PR expressions. Higher TOP2a and Ki67 expressions were correlated with shorter overall survival. Higher TOP2a expression and RacGAP1 positivity were directly correlated with shorter disease-free survival. Conclusion. This study showed that the overexpressions of Ki67, RacGAP1, and TOP2a affect the prognosis adversely, thus to develop target therapies against RacGAP1 and TOP2a as well as using Ki67 as a part of routine pathology practice might be beneficial in breast cancer therapy and prediction of prognosis.