Analysis of KI67 as a Prognostic Marker in Patients with Breast Cancer

Abstract

BACKGROUND: Ki67 is used to evaluate the proliferative activity of breast cancer. Its role as prognostic marker is not well defined though. Studies have suggested that Ki67 could be used to select patients who would benefitiate more from adjuvant chemotherapy. In this study we tried to observe the correlation between Ki67 expression and the indication of chemotherapy during breast cancer treatment, and its correlation with other prognostic markers. MATERIALS AND METHODS: Chat review of 332 women with invasive breast cancer who were followed between 2000 and 2009 at a private service, in Salvador, Brazil. A 20% Ki 67 cut-off was selected. RESULTS: Considering high Ki 67 >20%, we were able to study two distinct groups of patients. We observed a positive and statistically significant outcome between high Ki67 expression and low expression of oestrogen and progesterone receptors, greater tumor size and histologic grade, higher percentage of lymphovascular invasion, lymph node involvement and distant metastasis, and indication of adjuvant chemotherapy. There were numeric but not statistically significant correlations between Ki67 expression and HER-2 positivity, recurrent disease and use of chemotherapy for local recurrence and metastasis. DISCUSSION: We observed an association between high Ki67 expression and markers that indicate worse prognosis in patients with breast cancer. Patients with Ki67 higher expression are more likely to use adjuvant chemotherapy. CONCLUSION: in this study, high Ki67 was related to prognostic markers as absence of hormonal receptors, greater tumor size and histologic grade, higher percentage of lymphovascular invasion, lymph node involvement and distant metastasis, and indication of adjuvant chemotherapy.