366P - The impact of additional prognostic information obtained from Ki-67 changes after neoadjuvant chemotherapy varies in subtype of breast cancer

Date 29 September 2012
Event ESMO Congress 2012
Session Poster presentation I
Topics Biomarkers
Breast Cancer, Locally Advanced
Presenter Nobuaki Matsubara
Authors N. Matsubara1, H. Mukai1, Y. Naito2, M. Nezu1, K. Itoh1
  • 1Oncology And Hematology, National Cancer Center Hospital East, Kashiwa/JP
  • 2Dept. Of Breast And Medical Oncology, National Cancer Center Hospital East, Kashiwa/JP

Abstract

Introduction

A reduction in the Ki-67 index after neoadjuvant chemotherapy has been reported to be associated with a favorable prognosis. The present study investigates whether a reduction in Ki-67 may be a predictive surrogate marker of favorable prognosis in each subtype of breast cancer.

Methods

A total of 385 patients who received neoadjuvant anthracycline followed by taxane chemotherapy and subsequent surgery for invasive breast cancer were analyzed retrospectively. By immunohistochemistry (IHC), patients were divided into 4 subtypes (Luminal A, Luminal B, Triple negative and HER2). Ki-67 was examined by IHC in pre-treatment core needle samples and post-treatment surgical excisional specimens. The relapse-free survival (RFS) rate was compared among each subtype.

Results

The median follow-up period was 56 months. The rate of pathological complete response was higher for HER2 (34.8%) and Triple negative (24.3%) subtypes than for Luminal B (8.3%) and Luminal A (3.8%) subtypes (p < 0.0001). A reduction in Ki-67 was observed in 58.5%, 83.4%, 70.2% and 74.2% of patients in the Luminal A, Luminal B, Triple negative and HER2 subtypes, respectively. The differences in RFS between patients whose Ki-67 was reduced and those not reduced were statistically significant for Luminal B (81.4% vs. 50.0%, p = 0.003), Triple negative (74.8% vs. 43.5%, p = 0.003) and HER2 (82.7% vs. 59.0%, p = 0.008). However, for Luminal A, the difference in RFS was not observed depend on the changes of Ki-67 (78.8% vs. 75.3%, p = 0.78).

Conclusions

The reduction in Ki-67 after neoadjuvant chemotherapy is a predictive surrogate marker of a favorable RFS. However, this conclusion could not be applied to Luminal A subtype.

Disclosure

All authors have declared no conflicts of interest.