To study the immunotyping changes of HER2 positive breast cancer after neoadjuvant chemotherapy.

A retrospective analysis was made on 66 cases of breast cancer of HER2 positive treated with neoadjuvant chemotherapy from January 2012 to December 2017. All patients underwent ultrasound-guided core needle biopsy before chemotherapy, and pathological examination after surgery. SPSS19.0 statistical software was used to observe the changes of estrogen receptor (ER), progesterone receptor (PR), cell proliferation nuclear antigen Ki67 (Ki67) and HER2 levels in patients before and after adjuvant chemotherapy. Chi-square test was used to show that there was significant difference between patients before and after adjuvant chemotherapy with P<0.05.

After neoadjuvant chemotherapy in 66 HER2-positive breast cancer patients, PR up-regulated rate was 19.32%, and down-regulated rate was 25.57%. ER remained unchanged (74.43%). Ki67 down-regulated rate was 23.86%, which was significantly higher than the up-regulated rate of 12.50%, and the unchanged rate was 63.64%. 7 of 66 patients turned negative after neoadjuvant chemotherapy in HER2. The negative conversion rate was 10.61%.

ER and PR of some patients with HER2-positive breast cancer after neoadjuvant chemotherapy may be up-regulated or down-regulated. Ki-67 may be down-regulated in a certain proportion and HER2 may be negative. These changes will affect the classification of breast cancer and the choice of post-operative therapeutic drugs.