Effect of neoadjuvant chemotherapy on oestrogen, progesterone, and HER-2 receptor expression in breast cancer

Abstract

e11588 Background: Neoadjuvant chemotherapy(NC) is used in treating locally advanced operable breast cancer. After surgery, further adjuvant treatment is offered based on the estrogen receptor (ER), progesterone receptor (PR) and HER2 status. Treatment post operatively can be based on the ER/PR/HER2 status of the core biopsy taken preoperatively. It is not a usual practice in the United Kingdom to repeat these markers on the surgical specimen. However a change in ER/PR or HER2 status following NC could have a profound effect on adjuvant treatment with the real possibility of appropriate therapy being unknowingly withheld. The aim of our study was to determine the percentage of patients whose ER/PR, HER2 receptor expression change with NC and if these changes lead to change in their adjuvant treatment. Methods: This is a retrospective study of 32 patients with locally advanced breast cancer who had NC followed by breast conservation surgery or mastectomy. Quick score (Q score) for ER/PR and the HER2 expression was measured both from the preoperative core biopsy and from the excision specimen following NC. Results: After NC, 5 patients had complete pathological response and 2 patients had residual ductal carcinoma in situ. 25(78%) patients had residual invasive malignancy. Quantitative change in Q scores for ER and PR was seen in 6 patients(24%) and 10 patients (40%) respectively. ER status changed from positive to negative in 1 patient(4%). PR status changed from positive to negative in 4 patients(16%) and from negative to positive in one patient (4%). One patient(4%) changed from HER2 negative to HER2 positive after NC. Conclusions: Change in 1 patient(4%) from HER2 negative to HER2 positive lead to change in adjuvant treatment who would have otherwise not received transzutumab.Q scores changed in 24% and 40% for ER and PR respectively, however, no change was observed with regards to hormonal adjuvant treatment. A study with a bigger cohort might address this issue. We suggest that ER/PR/HER2 status should routinely be checked in both core biopsy sample and also resection specimen. No significant financial relationships to disclose.