Neoadjuvant chemotherapy may decrease tumor volume to allow breast conservation surgery. Its effect on estrogen and progesterone receptor (ER/PR) expression and hormone receptor (HR) status is controversial.

From February 2001 to July 2002, 56 breast cancer patients treated with neoadjuvant chemotherapy and 56 non-neoadjuvant therapy (control) patients with adequate tissue samples were identified. Quantitative ER/PR expression was analyzed in preneoadjuvant or preoperative core biopsies and final surgical specimens. Changes between the two groups were compared to determine if alterations were due to neoadjuvant chemotherapy or tissue sampling.

The ER/PR expression changed in 34 (61%) neoadjuvant chemotherapy patients and 27 (48%) control patients. These expression changes resulted in HR status (positive/negative) alterations in 3 patients (5%) in both groups. Age, histology, chemotherapy regimen, and neoadjuvant response did not predict change.

Hormone receptor status changed in 5% of neoadjuvant chemotherapy and control groups due to tissue sampling. As these changes may impact treatment, HR expression reanalysis in final surgical specimens is recommended.