Newer Drug Beats Tamoxifen for Older Breast Cancer Patients

ByABC News
August 19, 2009, 8:20 PM

Aug. 20 -- WEDNESDAY, Aug. 19 (HealthDay News) -- For postmenopausal women with breast cancer, treatment with the drug letrozole (Femara) increases survival after surgery more than the widely used tamoxifen, a new study confirms.

Both letrozole and tamoxifen have been used to prevent recurrence of breast cancer in postmenopausal women with hormone receptor-positive cancer, but whether one drug is better than the other has been unclear. The new study compared the impact of the newer drug, letrozole, to tamoxifen.

"This study reinforces the benefits of letrozole over tamoxifen, and leaves five years upfront use [of letrozole] as the preferred option, especially in patients judged to be at higher risk for recurrence," said lead researcher Dr. Alan Coates, co-chair of the scientific committee of the International Breast Cancer Study Group and a clinical professor in the School of Public Health at the University of Sydney, Australia.

The report is published in the Aug. 20 issue of the New England Journal of Medicine.

For the study, Coates and colleagues randomly assigned more than 8,000 postmenopausal women with hormone receptor-positive breast cancer to treatment with tamoxifen or letrozole for five years. In addition, some of the women were assigned to switch medicines after two years.

The study shows strong, though not incontrovertible, evidence that letrozole prolongs overall survival in comparison to tamoxifen, and that "this would in all probability have been conventionally significant had the switch of therapy not occurred," Coates said.

The other question in the study was whether the letrozole should be given before or after a period of tamoxifen therapy, Coates said.

"Neither sequence was superior to five years of straight letrozole," he said. "We found that the differences were small, but that consistently in the higher risk subgroups there was a benefit to starting with letrozole."

The study also included starting with letrozole and switching to tamoxifen, Coates noted.