Effect of neoadjuvant chemotherapy on expressions of estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2, and Ki-67 in breast cancer

Background This study was designed in an attempt to determine the influence of neoadjuvant chemotherapy on estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (Her-2), and Ki-67 expressions in patients with breast cancer.

Methods Pre- and post-neoadjuvant chemotherapy, paired-tumor specimens from 103 patients with breast cancer administrated with anthracycline or anthracycline combined taxane regimen were collected. Immunohistochemical staining for ER, PR, Her-2, and Ki-67 was performed by the DAKO EnVision method.

Results Among the 103 cases, five patients (4.9%) had a complete response (CR), 82 (79.6%) partial response (PR), 15 (14.6%) stable disease (SD), and one (0.9%) progressive disease (PD), yielding an overall response rate (CR + PR) of 84.5%. Nine patients achieved pathological CR. There was a significant decrease in the average index of Ki-67 post-neoadjuvant chemotherapy, compared with that before chemotherapy (24.1% vs. 39.7%, P <0.001). After neoadjuvant chemotherapy, the changes of Ki-67 in different subtypes of breast cancer were different (P <0.001), and these changes correlated with response to neoadjuvant chemotherapy (P <0.001). No significant changes in immunohistochemical expression were observed for ER, PR and Her-2.

Conclusions Neoadjuvant chemotherapy apparently reduced Ki-67 index in primary breast carcinomas, but profiles for ER, PR and Her-2 were not significantly different before and after neoadjuvant chemotherapy. The change of Ki-67 correlated with molecular subtypes and response to neoadjuvant chemotherapy, suggesting that Ki-67 index was a surrogate marker to predict the treatment response of neoadjuvant chemotherapy.