Exemestane (E) vs tamoxifen (T) as neoadjuvant endocrine therapy for postmenopausal women with ER+ breast cancer (T2N1–2, T3N0–1, T4N0M0)

Abstract

530 Background: There is considerable evidence that aromatase inhibitors are superior to T as first line endocrine therapy for metastatic disease. E an aromatase inactivator, is effective in women whose tumor has progressed despite T therapy. Methods: 151 PM women with ER+ breast cancer (BC) were randomly assigned once-daily treatment with either E alone 25 mg (n=76), or T alone (n=75) for 3 months. The primary endpoint was clinical objective response (OR). Secondary endpoints were OR determined by mammography and ultrasound, and number of pts who underwent breast conserving surgery (BCS). Result: Clinical, mammography, BCS rate are shown in the table. A pathological CR was shown in two pts in the E group and 2 pts in the T group. Response to any type of endocrine treatment was more likely in pts with higher levels of ER expression. Median time to response was 57 days in the E group and 70 days in the T group (p<0.05). All pts with disease progression after endocrine treatment were recommended to receive chemotherapy AT (doxorubicine 60 mg/m2 + paclitaxel 200 mg/m2, every 3 weeks to 4 cycles). Clinical OR after chemotherapy (second line neoadjuvant treatment) was 59.6%. During 50 months of follow up local recurrences were detected in 5.2% pts of E group and 8% pts in T group (p>0.05). 3-year disease free survival rates were 78.9% in E group and 74.6% in T group (p>0.05). Conclusion: E is more effective than T as neoadjuvant therapy for PM pts with ER+ tumors in rate of clinical OR and BCS. No significant financial relationships to disclose.