But the issue of bone loss alone is not a reason to avoid an aromatase inhibitor. That's because the aromatase inhibitors work better than tamoxifen and have become the standard of care for postmenopausal women with hormone-receptor-positive breast cancer.
This analysis of some of the ATAC study data looked at the amount of bone loss during hormonal therapy. But it didn't study the steps you can take to limit bone loss during hormonal therapy. The good news is that there are a number of things you can do to strengthen your bones while taking hormonal therapy.
Before you start taking any hormonal therapy, ask your doctor about having a DEXA scan to check your bone density. And while on hormonal therapy, you should have your bone density checked every 1 or 2 years.
No matter what hormonal therapy you're on, it's important to keep your bones strong by:
If you already have low bone density—osteopenia or osteoporosis—you need to pay extra attention to your bones. And if you're going to take an aromatase inhibitor, extra special attention is required. Your doctor will probably recommend a bone-building medicine like Actonel, Fosamax, or Boniva.
The goal of your hormonal therapy is to get the most benefits with the fewest side effects. In order to figure out your options, you and your doctor will have to consider the nature and extent of the cancer, your medical condition, menopausal status, and other treatments you have taken or are taking now. Overall, aromatase inhibitors have relatively few serious or unmanageable side effects. Less than 1% of women will have serious side effects that require stopping the medicine. Bone loss IS a problem with aromatase inhibitors, but it can usually be managed. And tamoxifen remains a very good option for many women.
Reviewed study: "Five Years of Arimidex Can Cause Bone Loss in Women With Low Bone Density" by R.E. Coleman and others, American Society of Clinical Oncology Annual Meeting, June 2006, Abstract 511
Is this for me? If you're considering taking Arimidex for 5 years instead of tamoxifen and have low bone density, you might want to read this article.
What question is this study trying to answer? The researchers wanted to know how 5 years of Arimidex (chemical name: anastrozole) affects bone strength compared with 5 years of tamoxifen.
Breastcancer.org previously reported on this study, known as the Arimidex, Tamoxifen, Alone or in Combination (ATAC) Trial.
Study design: The ATAC Trial studied postmenopausal women with early-stage breast cancer. About 84% of the cancers were hormone-receptor-positive. The women were randomly split into 3 equal groups:
The women in Groups 1 and 2 took the medicines for 5 years or until the breast cancer came back. (After a few years of being in Group 3, women in that group were given the option of joining Group 1 because the results of Group 1 were better.) For this report, the researchers looked at 81 women who received only Arimidex and 86 women who received only tamoxifen.
Results: Taking Arimidex for 5 years can lead to a 6% to 7% bone density loss in women who are borderline osteopenic (have lower bone density than normal) when they begin treatment.
Women who have normal bone density when they start taking Arimidex are unlikely to develop osteoporosis (bone mass is below normal, and bones are at higher risk of breaking).
For the women in this analysis, the rate of bone density loss decreased over time. The bone loss was higher in the first 2 years of treatment than during the last 3 years of treatment. After 5 years, women taking Arimidex lost 6% of bone density at the hip and 7% at the spine, compared with losses of 3% at the hip and 0.7% at the spine in women taking tamoxifen.
Women who took Arimidex for 5 years had a 40% increase in the relative risk of broken bones. When the women quit taking Arimidex, the risk decreased. Relative risk is the number that tells you how much something you do, like taking Arimidex, can change your risk, compared with your risk while taking another medication.
About 11% of the women taking Arimidex had broken bones, compared with about 8% of the women taking tamoxifen. This difference was statistically significant, which means that it was probably due to the Arimidex and not just to chance.
It wasn't clear if the women in each group took other steps to reduce bone loss while on hormonal therapy.
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