The disease-free survival rate increased significantly among women who made the switch.
The American Society of Clinical Oncology has stated that “optimal adjuvant hormonal therapy for a postmenopausal woman with receptor-positive breast cancer includes an aromatase inhibitor as initial therapy or after treatment with tamoxifen.” Aromatase inhibitors, which block estrogen synthesis, improve disease-free survival when hormone-sensitive breast cancer becomes resistant to tamoxifen, and they have outperformed tamoxifen as initial adjuvant therapy.
In 2004, researchers reported on 4700 postmenopausal women with breast cancer of positive or unknown estrogen receptor status who were disease free after 2 to 3 years on tamoxifen; the women were randomized to complete the remainder of 5 years of adjuvant therapy with either tamoxifen or…