Study Confirms Letrozole Better than Tamoxifen
(American Cancer Society, 6/17/03)

When the hormone, estrogen, attaches to protein receptors on the outer surfaces of breast cells, it signals the cells to grow. The drug, Tamoxifen, inhibits breast cancer growth by blocking estrogen from attaching to the receptors, but unfortunately this drug often loses its effect over time. Now researchers have developed aromatase inhibitors, which prevent estrogen from being produced at all. In an international study, investigators gave more than 900 postmenopausal women with advanced breast cancer either tamoxifen or letrozole, switching them if the one they were taking failed to work. Compared to those taking tamoxifen, subjects on letrozole were able to take the drug longer, had more time before the cancer progressed and were more likely to have their tumors shrink by at least half. These findings suggest that letrozole is superior to tamoxifen for treating postmenopausal women with advanced cancer.

(Journal of Clinical Oncology, Vol. 21, No. 11: 2101-2109)