Drug Cuts Breast Cancer in High Risk Women By 50%

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Women with a high risk for breast cancer can cut their chances of developing the disease by 53% with the drug anastrozole after five years during a study.

The finding, published in the journal the Lancet and presented at the San Antonio Breast Cancer Symposium, came from 4,000 postmenopausal women with a family history of breast cancer or other risk factors, half of whom took 1mg of anastrozole (Arimidex) every day and the other half who took placebo. After five years, 40 of the women taking anastrozole developed breast cancer and 85 women in the placebo group developed the disease.

The medication belongs to a group of drugs known as aromatase inhibitors (AIs) that lower estrogen-fueled breast cancers by inhibiting production of the hormone. The drugs are more effective in post menopausal women, who no longer produce estrogen in the ovaries. But until recently, the three AIs approved by the Food and Drug Administration have been used primarily to control recurrent tumors.

Earlier this year, however, breast cancer experts started recommending that one of these medications, exemestane (Aromasin), be used to prevent breast cancers in high risk women who had not yet developed the disease. Currently, women in this population take tamoxifen and other estrogen-lowering drugs, but these have side effects such as muscle pains and extreme fatigue that prevented some women from taking advantage of them.

The latest results, however, showed that the side effects of anastrozole were only slightly higher than those caused by the placebo.

“Our priority now is ensuring that as many women as possible can benefit from these new findings. Prevention is an important tool in the fight against breast cancer,” said study author Jack Cuzick, the head of Queen Mary University of London’s Centre for Cancer Prevention in a statement. Cuzick urged the UK’s National Institute for Health and Care Excellence (NICE) to consider adding anastrozole to the drugs it recommends for women at high risk of developing breast cancer.

Whether U.S. organizations will act on the data isn’t clear yet. Some experts note that the data, while encouraging, isn’t solid enough for anastrazole to join exemestane as a preventive measure, since studies documenting the fact that women taking anastrazole enjoyed lower death rates from breast cancer with fewer side effects than existing drugs have not been conducted yet.