Objective To investigate the correlation between pathologic complete response (pCR) rate and neoadjuvant chemotherapy cycles under different estrogen receptor (ER) status of breast cancer.

Methods We retrospectively analyzed the complete clinical data of 430 breast cancer patients in the Tumor Hospital Affiliated to Zhengzhou University from April 1st, 2012 to March 30th, 2016. According to the ER status, the patients were divided into ER+ and ER-groups, and neoadjuvant chemotherapy cycles were divided into 3-4 and 6-8 cycles. The pCR rate of different neoadjuvant chemotherapy cycles were analyzed by χ² test. The predictors of pCR rate were analyzed using multivariate logistic regression analysis.

Results Of 430 patients, the pCR rate were 24.0%(103/430). Compared with 3-4 chemotherapy cycles, the pCR rate was increased in 6-8 cycles in ER+ group, and the difference was statistically significant (χ²=7.924, P < =0.005), while the increased pCR rate was not statistically significant in ER-group (χ²=0.018, P < =0.893). Multivariate logistic regression analysis showed that the chemotherapy cycles (P < =0.009), targeted therapy (P < =0.007), primary tumor size (P < =0.000) were the independent predictors of pCR rate in all patients. The stratified analysis of ER status showed that the chemotherapy cycles was an independent predictor of pCR rate only in ER+ patients (95%CI: 0.175-0.784, P < =0.009).

Conclusion Compared with 3-4 chemotherapy cycles, 6-8 cycles of chemotherapy can significantly improve the pCR rate in ER+ patients, but no significantly increased pCR rate in ER-patients.