Drug May Be New Option to Cut Breast Cancer Risk
Study Shows Aromasin May Help Prevent Breast Cancer in High-Risk Women
Tracking Breast Cancer Risk continued...
About half of the women enrolled in the study were over age 60.
The average age of study participants was 62.5 years and the midpoint of their Gail scores was 2.3%.
The women were then randomly assigned to receiver either 25 milligrams of Aromasin daily or a placebo pill. Neither the women nor their doctors knew who was getting treatment or placebo.
Researchers gave the women annual checkups, including a yearly mammogram.
After about three years of follow-up, 43 invasive breast cancers were diagnosed: 11 in the Aromasin group and 32 in the placebo group.
Overall, 0.55% of women in the placebo group and 0.19% of women in the Aromasin group were diagnosed with breast cancer each year during the study, a reduction in risk of about 65% for women taking the drug.
Stated another way, researchers found that 94 women would need to take the drug for three years to prevent one case of cancer. That number dropped to just 26 women to prevent one diagnosis of breast cancer after five years.
The majority of cancers in both groups were estrogen receptor positive, a kind of cancer that tends to respond well to treatment.
In women who had previously used hormone replacement therapy, Aromasin had slightly greater effect, reducing the risk of cancer by 70% compared to placebo.
The study wasn't able to show that the drug improved overall survival, however.
Adverse events were reported by 88% of women on Aromasin and 85% of women taking the placebo.
Arthritis and hot flashes were slightly more common in the treatment group.
There were no differences between the groups in the numbers of women who were newly diagnosed with osteoporosis or cardiovascular events.
Serious adverse events in the study were rare and none were judged to be attributable to Aromasin.
The study was sponsored by the Canadian Cancer Society Research Institute, the Canadian Institutes of Health Research, the Avon Foundation, and Pfizer, the company that makes Aromasin.