A retrospective and prospective study of response to aromatase inhibitors and TAM in HER2-overexpressed postmenopausal breast cancer patients

Abstract

11577 Background: Observe response to aromatase inhibitors and TAM in HER2-overexpressed postmenopausal breast cancer patients. Methods: Collect 501 patients given tamoxifen (TAM 2.5mg Qd, po) and 232 patients given aromatase inhibitors (letrozole 10 mg Bid, po) from 2002.7 to 2005.3. Select randomly 300 cases from 2004.8 to 2005.8. Randomly give tamoxifen or aromatase inhibitors. All patients are postmenopausal and ER-positive. Results: Retrospective study results: 1. In TAM group, 3-year DFS of HER2- overexpressed ones is lower than that of HER2-negative ones. (1) No difference existed between HER2-overexpressed and HER2-negative ones in node-negative group. But difference existed in node-positive group (p=0.037). (2) In HER2-overexpressed group, ER+/PR+ ones is higher than ER+/PR- ones. 2. In AIs group, no difference between HER2-overexpressed and HER2-negative ones. (1) Also no difference in node- positive or node-negative group. (2) In HER2-overexpressed group, ER+/PR+ is higher than that of ER+/PR-. Prospective study results: 3-year DFS of patients treated with AIs is higher than that of TAM. (1) In HER2- overexpressed group, AIs is higher than TAM (p=0.024); but no difference in HER2 negative group.(2) In node-positive group, AIs vs TAM is 89.7% vs 88.5% (p=0.04); no difference in node-negative group. (3) In ER+/PR-group, AIs is higher than that of TAM. And also in ER+/PR- group. (4) In node-positive patients with HER2-overexpression, 3-year DFS of AIs is higher than that of TAM. (5) Safety: hot flushed, vaginal bleeding and thromboembolic of AIs group is much lower, but muscle pain and bone fracture is higher than TAM group (p<0.05). AIs couldn’t increase risk of endometrial cancer and thromboembolic. Conclusions: Retrospective study shows HER2-overexpressed patients will resistant to TAM therapy; but HER2 expression won’t influence postmenopausal node-negative ones. Prospective study suggested HER2-overexpressed patients are sensitive to aromatase inhibitors and won’t be influenced by node status; AIs is more effective for postmenopausal patients with ER-positive or HER2- overexpressed ones; AIs has good tolerance and safety. No significant financial relationships to disclose.