Letrozole in the extended adjuvant setting: MA.17
1Massachusetts General Hospital Cancer Center, 55 Fruit Street, Cox Bldg., Room 640, Boston, MA 02114, USA. pgoss@partners.org
Breast Cancer Research and Treatment
|November 21, 2007
Summary
Letrozole significantly improves disease-free survival for women with hormone-responsive breast cancer after tamoxifen therapy. Extended letrozole treatment offers a survival advantage, showing tumors remain sensitive to hormone therapy.
Area of Science:
- Oncology
- Endocrinology
Background:
- Adjuvant tamoxifen therapy is standard for hormone-responsive breast cancer.
- Relapse remains a significant concern for patients completing tamoxifen treatment.
Purpose of the Study:
- To evaluate the efficacy of letrozole for extended adjuvant hormonal therapy after 5 years of tamoxifen.
- To determine if letrozole improves outcomes in postmenopausal women with hormone receptor-positive breast cancer.
Main Methods:
- A randomized trial (MA.17) involving 5,187 postmenopausal women with hormone receptor-positive breast cancer.
- Participants received either letrozole (2.5 mg daily) or placebo for 5 years.
- Disease-free survival (DFS) was the primary endpoint, with secondary endpoints including distant DFS and overall survival.
Main Results:
- Letrozole significantly improved DFS compared to placebo (HR=0.58, P<0.001).
- Significant improvements were observed in distant DFS (HR=0.60, P=0.002) and overall survival in node-positive patients (HR=0.61, P=0.04).
- Benefits were noted even in patients who switched to letrozole after unblinding, indicating sustained hormone sensitivity.
Conclusions:
- Letrozole is a well-tolerated and effective option for extended adjuvant therapy following tamoxifen.
- Consideration of letrozole for up to 5 years post-tamoxifen is recommended for disease-free patients.
- Tumor sensitivity to hormone therapy persists long after tamoxifen discontinuation.
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