Expression of ER, PgR, HER-2, and Ki-67 in core biopsies and in definitive histological specimens in patients with locally advanced breast cancer treated with neoadjuvant chemotherapy.

Purpose: Many studies have indicated that the response to therapy and the prognostic impact of a pathologic complete response after neoadjuvant treatment differ among breast cancer subtypes.

Methods: The aim of our study is to evaluate the effect of this treatment on the expression of estrogen and progesterone receptors, human epidermal growth hormone receptor 2 and Ki67 in breast cancer. We identified 125 patients.

Results: The estrogen receptor modified its expression from positive to negative in 8% patients and from negative to positive in 22%; progesterone in 21% and in 37% cases. Median Ki-67 value was 20.9% at biopsy and 18% after, HER-2 status did not show a remarkable change before or after neoadjuvant chemotherapy (NACT). We have identified a significant reduction in Ki-67 expression levels after chemotherapy in patients with a pathologic response. Detection of pretreatment Ki-67 could identify patients most likely to benefit from NACT.

Conclusions: NACT can change the status of ER, PgR, and Ki-67 expression in patients with breast adenocarcinoma, but it did not exert a significant effect on HER-2 status; HER-2 amplification appears to be more stable. We have identified a prognostic role for a decreased expression of PgR and Ki-67 after preoperative chemotherapy in breast cancer patients.