Femara Beats Older Breast Cancer Drug
Aromatase Inhibitor Better Than Tamoxifen in Head-to-Head Comparison
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Femara Cut Relapses, Side Effects
The new study, presented at the annual meeting of the European Society of Medical Oncology, followed 4,922 postmenopausal women who were given either tamoxifen or Femara after breast cancer surgery.
By 51 months later, Femara scored better than tamoxifen on almost every measure. It lowered the risk of relapse or dying by 18% more than tamoxifen, and it reduced distant metastases -- that is, cancercancer spread outside of the breast -- by 19% more than tamoxifen.
And in women whose cancer had already spread to the lymph nodes at the time of diagnosis and those who had not received chemotherapy, the risk of recurrence was reduced by 23% and 26% more than tamoxifen, respectively.
Also, for the first time, the longer-term results revealed emerging evidence that Femara may benefit women whose cancer had not spread to the lymph nodes at the time of diagnosis, Coates says. In this group of women, Femara reduced the risk of breast cancer coming back by 12% more than tamoxifen. In contrast, only a 2% difference was observed after two years of follow-up, he says.
As for side effects, both drugs were generally well tolerated, he says. More women on tamoxifen suffered vaginal bleeding, night sweats, and clots in the legs or lungs, Coates says.
But women taking Femara were more prone to slightly elevated cholesterol levels, joint pain, and bone fractures than those taking tamoxifen.
"But we now have drugs that can strengthen bones in women taking Femara," Coates says. "No woman who has normal bone densitybone density when she starts on Femara will develop osteoporosisosteoporosis."
The Next Step
While the study shows Femara appears to be more effective than tamoxifen, doctors are still figuring out how to best use the aromatase inhibitors.
Some studies suggest they work best right after breast cancer surgery, while others suggest women could cut their risk of recurrence even further by taking an aromatase inhibitor after they completed about five years on tamoxifen.
"What's clear is that Femara has an edge over tamoxifen," Coates says. "But whether the best strategy is an aromatase inhibitor alone, tamoxifen followed by an aromatase inhibitor, or an aromatase inhibitor followed by tamoxifen is the big question."
A second part of the current trial should offer answers to that question by next year, he says.
Breast cancer is the second biggest cancer killer of women in the industrialized world, after lung cancerlung cancer. It kills about 40,000 women each year in the U.S.