Ki-67, p53, and clinical outcomes of patients with triple-negative breast cancer.

Abstract

142 Background: Triple-negative breast cancer (TNBC) tends to produce a poor prognosis because of aggressive tumor biology and lack of targeted agents. Breast cancer with a high Ki-67 value responds better to chemotherapy but is associated with lower relapse-free (RFS) and overall survival rates. The basal-like subtype overlaps with TNBC in approximately 70% to 80% of the cases, and the vast majority of basal-like subtypes have mutated p53. The aim of this study was to evaluate the clinical and prognostic significance of Ki-67 and p53 in patients with TNBC. Methods: We retrospectively reviewed 1,711 patients with pT1-3 invasive breast cancer diagnosed between 2001 and 2010. Of the 200 TNBC cases, 165 patients received adjuvant chemotherapy. Cases were classified as luminal (ER+ and/or PR+ and HER2-), HER2 disease (HER2+) and TNBC (ER-, PR- and HER2-) subtypes. Estrogen receptor (ER) and progesterone receptor (PR) positivity was defined as ≥10% positive tumor cells with nuclear staining. Ki-67 was classified into the following three groups: low (<20%), intermediate (20-50%) and high (≥50%), and the p53 high group was indicated by ≥50% staining. RFS was compared according to the level of Ki-67 and p53. Results: Patients with a high Ki-67 value were frequently seen in 53% of the cases with TNBC (luminal: 6% and HER2 disease: 25%, p<0.0001). The greatest proportion of patients in the low p53 group were the luminal type (luminal: 7%, HER2 disease: 49%, TNBC: 54%, p<0.0001). A high Ki-67 value was not associated with poor RFS in TNBC (p=0.2734). A high p53 expression was associated with poor RFS (p=0.024). TNBC with adjuvant chemotherapy and a high p53 expression tended to produce poor RFS (p=0.0516). Conclusions: TNBC with a high Ki-67 value was not associated with poor prognosis in this study. However, p53 status could be a significant prognostic factor in TNBC patients, especially in adjuvant chemotherapy cases.