Proliferation-based prediction for overall survival in locally advanced HER2(+) breast cancer.

Abstract

e12007 Background: Breast cancer prognosis is influenced by several factors including Ki67 expression which may have a predictive role in luminal breast cancer patients. The aim of this study was to assess the value of Ki67 in breast cancers with positive hormonal receptors and HER2 overexpressed and to evaluate its impact on survival. Methods: Seventy eight consecutive patients diagnosed with locally advanced HER2 positive breast cancer who were treated with adjuvant therapy based on HER2 treatment were selected for this study (2004-2014). The adjuvant chemotherapy schemes were 44% TCH, 16% FEC, 11% AC/T and 29% other therapies. The median of followup was 68 months. Tumor proliferation was assessed immunohistochemically by Ki67 expression and calculated as percentage of stained tumor cells from this cohort previous to adjuvant chemotherapy administration and the results obtained were correlated with disease status and outcome. Results: High proliferation defined as a percentage > 15 of tumor cells was observed in 69% of the breast cancer patients cases. High proliferation significantly predicted longer overall survival (OS) (Log rank 0,012). At 10 years of follow-up, 93% of the patients with KI67 high expression were alive versus 43% of patients without overexpression. Multivariate analysis confirmed the clinical significance of Ki67 predicting OS for luminal HER2 breast cancer patients (p 0,04 y HR 9,6). Conclusions: High proliferation identifies a setting of luminal-B HER2+ subtype breast cancer patients with a significantly longer overall survival.