Exemestane as Neoadjuvant Hormonotherapy for Locally Advanced Breast Cancer: Results of a Phase II Trial

Background: Neoadjuvant hormonotherapy has recently been used for downstaging large or locally advanced (LA) breast cancer in postmenopausal women. Patients and Methods: A phase II study was conducted in postmenopausal, hormone-receptor (HR) positive, T2-T4 patients, receiving 25 mg/day exemestane for 16 weeks. Results: Among 42 patients, 57.1% underwent conservative surgery. The clinical objective response rate (ORR) was 73.3%, without progression. A pathological partial response was achieved in 16.7% of the patients. Exemestane significantly reduced the expression of Ki-67 and progesterone receptors (PgR) (p<0.001). A significant decrease in PgR was correlated with clinical ORR (p=0.028). The responders presented higher baseline PgR levels (p=0.017). No relationship was found between ORR and mRNA expression of aromatase or oestrogen receptors ‚ (ER- ‚). Conclusion: Neoadjuvant exemestane provided satisfactory efficacy and safety profiles in LA breast cancer. The main biological effects consisted of a reduction in PgR expression for responders and a decrease in Ki-67 expression. Preoperative neoadjuvant chemotherapy has been extensively assessed in women with large operable or locally