Abstract: Objective To explore the significance of neoadjuvant chemotherapy(NAC)in the treatment of breast cancer and to identify the possible applicable population, to investigate the effects of NAC on the expressions of estrogen receptor(ER), progesterone receptor(PR), human epidermal growth factor receptor 2(Her-2)and Ki-67, and to evaluate the prognostic value of such expression changes. Methods Clinical data of 2,928 female breast cancer patients treated in our hospital during Jan. 2009 and Dec. 2017 were retrospectively analyzed. After screening with inclusion and exclusion criteria, 1,817 cases were included. COX regression was used to analyze the effects of clinicopathological indicators on the prognosis of patients in NAC group and adjuvant chemotherapy group, including age, tumor size and lymph node status at initial diagnosis, menopause, number of lymph node metastasis, and molecular classification. According to the effects of NAC on the expressions of ER, PR, Her-2 and Ki-67, the prognostic value of the changes in these molecular markers was explored. Results In the NAC group, patients with tumor size ≤5 cm, metastatic lymph nodes ≥4 and triple negative breast cancer had the highest survival benefits, while patients aged 50-80 years, with negative lymph node at initial diagnosis, menopausal and Her-2 positive had the lowest survival benefits. Patients aged 20-49 years, with tumor size >5cm, lymph node positive at initial diagnosis, premenopausal, metastatic lymph nodes <4, and Luminal type breast cancer were associated with high recurrence risk. There were significant differences in ER, PR and Ki-67 expressions before and after NAC(P<0.05), while there was no significant difference in Her-2(P=0.754). There was no significant correlation between the changes of ER, PR and Her-2 before and after NAC with overall survival(OS)and disease-free survival(DFS)(P>0.05). Compared with patients with stable and decreased expression of Ki-67, patients with low to high expression of Ki-67 had poorer survival benefits(P<0.05). Conclusion NAC is not suitable for all patients with operable breast cancer. Survival benefits should be evaluated comprehensively based on patients age, tumor size, lymph node metastasis status, molecular typing and other pathological indicators as well as breast preservation willingness. NAC can change the expressions of ER, PR and Ki-67 in breast cancer, and the expression of Ki-67 can be considered as a predictive marker of the effects of NAC.

Key words: Breast cancer, Neoadjuvant chemotherapy, Molecular subtyping, Estrogen receptor, Progesterone receptor, Ki-67 antigen