Skip to content

Breast Cancer Health Center

Font Size

Drug May Be New Option to Cut Breast Cancer Risk

Study Shows Aromasin May Help Prevent Breast Cancer in High-Risk Women

Risks vs. Benefits continued...

Aromatase inhibitors have been shown to cause some bone loss, which can be reversed, and many women find that symptoms associated with menopause like hot flashes, insomnia, fatigue, and arthritis get worse while on the medications.

In the current study, however, about the same number of women reported those kinds of side effects in the placebo group compared to those taking Aromasin, suggesting little difference on or off the drug.

There were no major differences between the two groups in terms of fractures, cardiovascular events, other kinds of cancer, or treatment-related deaths.

Oncologists say the new study means that more women can, and probably should, be on the medications.

Tracking Breast Cancer Risk

Starting in 2004, researchers enrolled 4,560 postmenopausal women.

In order to be included in the trial, women had to be either over age 60 or they had to be over age 35 with a Gail risk score of 1.66% or higher or have a history of in situ cancer. A Gail risk score calculates the five-year risk of developing breast cancer based things like family history, age, race, and childbearing history.

Women weren't eligible if they were premenopausal, because Aromasin doesn't work in women with functioning ovaries.

They were also excluded if they'd had a diagnosis of invasive breast cancer; were known carriers of the BRCA1 or BRCA2 genes; had history of other kinds of invasive cancer within the last five years; or had uncontrolled thyroid or liver disease.

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.

Today on WebMD

Breast Cancer Overview
From self-exams and biopsies to reconstruction, we’ve got you covered.
Dealing with breast cancer
Get answers to your questions.
woman having mammogram
Experts don’t agree on all fronts, but you can be your own advocate.
woman undergoing breast cancer test
Many women worry. But the truth? Most abnormalities aren’t breast cancer.
Breast Cancer Treatments Improving
Resolved To Quit Smoking
Woman getting mammogram
Screening Tests for Women
ovarian cancer overview slideshow
serious woman
what is your cancer risk
10 Ways to Revitalize Slideshow