A new approach to reducing breast cancer recurrence

In a long-running clinical trial, the drug letrozole (Femara) has proven significantly more effective than tamoxifen, the standard of care for post-operative treatment of women whose breast cancers were estrogen-receptor positive meaning sensitive to estrogen. The study, just published in The Lancet Oncology, found that letrozole was 20 percent more effective both at reducing the chances of breast cancer recurrence, as well as at increasing women s chances of survival.

About 60 percent of all breast cancers are estrogen-receptor positive. Tamoxifen works by blocking estrogen receptors, while letrozole inhibits an enzyme that is necessary for the production of estrogen, thus reducing the level of the hormone.

The study followed over 8,000 postmenopausal women for an average of about eight years after breast cancer surgery, separating them into several groups: one group was given letrozole alone or tamoxifen alone for five years, while the other two groups were given both drugs in sequence one of the drugs for two years followed by the other for three years. The outcomes revealed that letrazole clearly outperformed tamoxifen.

This finding is very important to a lot of women, ACSH s Dr. Ruth Kava observes. For over 30 years, Tamoxifen has been widely used for women whose breast cancer is estrogen-receptor positive. Indeed, since letrozole is currently given alone or in sequence with tamoxifen, the results of this major study may very well change the standard of care.