Response to primary chemotherapy in breast cancer patients with tumors not expressing estrogen and progesterone receptors

Background: We recently demonstrated that in premenopausal patients with estrogen receptors (ER)-absent tumors, early initiation of systemic chemotherapy after primary surgery might improve outcome. These data indicate a different responsiveness to chemotherapy for tumors not expressing hormone receptors. To test this hypothesis we evaluated the responsiveness to preoperative chemotherapy in patients with ER and progesterone receptors (PgR)-absent tumors. Patients and methods: Patients with biopsy-proven T₂-T₃, N_0-2 breast cancer treated at a single institution from January 1995 to August 1999 with preoperative chemotherapy were retrospectively evaluated. ER and PgR were determined immunohistochemically and classified for this purpose as absent (0% of the cells positive) or positive (≥ 1% of the cells). Results: On 117 evaluable patients 72 had an objective response (61%). A significant difference in response was observed for patients with ER and PgR absent compared with those with ER and/or PgR-positive tumors (82% vs. 57%, P = 0.03 Fishers's exact test). Pathological complete remission rates were also significantly different in the two groups (23% vs. 7%, respectively; P = 0.04). Conclusions: The different degree of response according to hormone receptors expression supports the hypothesis that tumors not expressing both ER and PgR might represent a different clinical entity in terms of chemotherapy responsiveness.