Purpose: To evaluate the utility of Ki67 as a prognostic marker in Luminal B node-negative breast cancer patients.
Methods: We identified 888 patients with invasive breast carcinomas who underwent surgery between 1997 and 2004. Several classical factors were collected: age, tumor size, node involvement, tumor grade, estrogen and progesterone receptors, HER2 and Ki-67 expression. We analyzed if these parameters could be considered as a prognostic factor. In early Luminal B group, we investigated which of the following biological features provide information about bad prognosis: lack of progesterone receptor expression, HER2 overexpression/amplification or high Ki-67 value.
Results: The majority of patients were alive and without relapse of tumor at the moment of the analysis (70 %). The prognostic factors founded in multivariate analysis were: tumor size, node involvement, grade 3 and Ki-67 expression. When we stratified the sample by immunohistochemistry (IHC) in tumor subtypes, we assessed 680 patients and we observed 191 Luminal B tumors. The biological parameter related to the worst survival in absence of nodal involvement was Ki-67 value.
Conclusions: Ki-67 represents an additional predictor of survival in Luminal B node negative breast cancer. Conversely, neither Progesterone-receptor nor HER2 status proved prognostic significance in this group in our study.
Keywords: Immunohistochemistry; Ki-67; Overall survival; Prognostic factor; Tumor proliferation marker.