Breast Cancer and Your Bone Health: What To Know

When you’re diagnosed with breast cancer, bone health might not be on the top of your mind. But it is for your care team.

That’s because some breast cancer treatments can weaken your bones, raising your risk for osteoporosis and fractures.

We talked with breast medical oncologist Megan Kruse, MD, about how breast cancer can affect your bones — and how your team will monitor and protect your bone health during treatment and beyond.

How does breast cancer affect your bones?

Breast cancer itself doesn’t cause changes to your bones. But treatments like hormone therapy and chemotherapy can lead to bone loss.

“These treatments are incredibly effective,” Dr. Kruse emphasizes. “But we have to recognize the downstream effects and have a plan to minimize your risk. Our goal is to make treatment as tolerable and safe as possible over the long term.”

That’s why your oncologist and other members of your care team might talk with you about monitoring your bone density and taking steps to keep your bones strong as part of your treatment plan. That can be especially true if cancer care affects your estrogen levels or accelerates menopause.

Dr. Kruse explains how some common breast cancer treatments can affect bone health.

Hormone therapy and estrogen

If you have hormone receptor–positive breast cancer (HR+), your cancer cells are fueled by hormones — typically estrogen (ER+).

Oncologists can treat these cancers with hormone therapy to lower your estrogen levels. That effectively cuts off the cancer at the source. Without estrogen, those cancer cells can’t grow.

But there’s another side to that coin. Your bones rely on estrogen to stay strong. So, when you take hormone therapy for breast cancer, it can weaken them.

“When estrogen levels drop — because of natural menopause or cancer treatment — you can lose bone density quickly,” Dr. Kruse reports. “Any time there’s a change in estrogen levels, we think about bone health, too.”

Not all hormone therapies affect your bones the same way. And their effect on your bone health can be factored in when your providers recommend the following treatments:

• Aromatase inhibitors, like anastrozole, lower estrogen levels throughout your body. Your provider may recommend these medications if you’ve already gone through menopause or if your ovarian function is being suppressed as part of your treatment.
• Tamoxifen works differently. It blocks estrogen in your breast tissue to starve the cancer. But it can act like estrogen in other parts of your body — including your bones. “For some people, tamoxifen can actually help protect bone density,” Dr. Kruse points out.

Chemotherapy

Chemotherapy doesn’t directly weaken your bones. But it can affect bone health indirectly, especially in younger people.

“Chemotherapy can sometimes trigger early menopause,” Dr. Kruse explains. “When that happens, estrogen levels drop sooner than expected, which can increase the risk of bone loss.”

Managing bone loss and breast cancer

You already know that a breast cancer diagnosis comes with a lot of appointments, treatments, tests and procedures. Some of those efforts will be specifically to keep tabs on your bone health.

Your providers may recommend bone density testing with DXA scans. These specialized X-ray tests show how strong your bones are and note any signs of bone loss.

“This kind of monitoring is preventive,” Dr. Kruse says. “It helps us understand where someone is starting and how things may change during treatment so we can protect your health for the long term.”

Depending on your bone health, menopause status and treatment plan, you may have an initial DXA scan before treatment and follow-up scans every one to two years to look for changes in your bones.

Your team may recommend other ways to keep your bones strong during and after treatment, too, including:

• Eating a balanced diet with plenty of fruits, vegetables and lean proteins
• Weight-bearing exercise, like walking, aerobics, yoga and strength-training
• Healthy habits, like not smoking, limiting alcohol and staying hydrated
• Supplements, like calcium and vitamin D
• Osteoporosis medications, like bisphosphonates

Final thoughts: Focus on your whole self

A breast cancer diagnosis comes with a lot of worries. The cancer itself may be your first concern. But then come the other nagging questions about your long-term health.

Even when cancer takes its toll, it doesn’t have to take your strength. Talk with your team about plans for keeping your whole body healthy for the long haul. They can help you understand your risks and determine a plan to best support your bones — and the rest of you.

“We don’t look at bone health in isolation,” Dr. Kruse says. “We look at the whole person, their treatment history and what they need going forward.”