Osteoporosis and Breast Cancer

Medically Reviewed by Melinda Ratini, MS, DO on April 06, 2024
5 min read

As breast cancer treatments improve, more women are living longer with the condition. Nearly 4 million breast cancer survivors are alive in the United States today. Many of them could be at risk for another disease: osteoporosis. This disease makes your bones thinner and more likely to fracture.

Not only can breast cancer itself weaken your bones, but treatment for it can, too. And if you have weak bones, you may not know it. Some people call osteoporosis a "silent" disease because it may not cause noticeable symptoms for a long time.

The more you know about your osteoporosis risks, the better you can protect your bones during your treatment and as you age.

Breast cancer is more common in women 60 and older. Your osteoporosis risk also goes up at this age. That happens in part because your estrogen levels drop after menopause, and estrogen helps keep your bones strong.

Breast cancer can weaken bones. Cancer causes inflammation in your body that speeds up the breakdown of old bone and slows new bone growth.

Up to 80% of postmenopausal breast cancer survivors lose bone mass. Survivors under 50 have nearly twice the risk of osteopenia (bone density loss) and osteoporosis (more serious bone thinning and weakening) as women who’ve never had cancer.

It’s not only the disease itself that contributes to bone loss. Some breast cancer treatments, like hormone therapy and chemotherapy, weaken bones, too. These treatments increase your risk for osteopenia, which can then progress to osteoporosis and eventually broken bones.

Bone loss from cancer treatment happens much faster and is more intense than natural bone loss that happens as you age. You can lose up to seven times more bone from cancer treatment than you would from aging alone.

Hormone therapies for breast cancer are one type of treatment that puts your bones at risk.

About 2 out of every 3 breast cancers are hormone receptor-positive. This means the hormones estrogen or progesterone help the cancer grow. Treatments for estrogen-receptor-positive breast cancers reduce, block, or stop your body’s release of estrogen in order to starve cancer cells of this natural fuel. But that means your bones lose out on this bone-strengthening hormone, too.

Women with early-stage, estrogen-receptor-positive breast cancer often get this type of treatment. It can be very effective against cancer, but it can put you into early menopause and increase your risk for bone loss at a younger age.

Here are some of the hormone-based and other breast cancer treatments that can weaken bones:

Tamoxifen. This medication stops estrogen from helping cancer grow. In women who haven't reached menopause, tamoxifen slightly increases the risk of osteoporosis. But in postmenopausal women, it lowers the risk.

Aromatase inhibitors (AIs). These medicines, which include anastrozole (Arimidex), exemestane (Aromasin), and letrozole (Femara), lower estrogen levels in your body. They can increase your risk for osteopenia and osteoporosis.

Ovarian suppression. These treatments stop your ovaries from making estrogen. The medicines goserelin (Zoladex) and leuprolide (Lupron) are a temporary form of ovarian suppression. Estrogen production restarts after you stop taking them. But sometimes you get surgery to remove the ovaries as part of breast cancer treatment. It's a permanent form of ovarian suppression. Having less estrogen in your body, even for a short time, can increase your risk for bone density loss.

Chemotherapy. This powerful treatment can also take a toll on bone health. These strong medicines kill cancer cells, but some can also damage the ovaries and put you into early menopause. Like the others, this treatment can increase your risk for osteoporosis.

You may be at even higher risk for osteoporosis if you’re in treatment for breast cancer and you:

  • Are age 65 or older
  • Smoke cigarettes
  • Have more than two alcoholic drinks on most days
  • Have had broken bones before
  • Used steroid medicines
  • Weigh less than 125 pounds

Talk to your doctor about your personal risk and whether you need screening for bone loss.

Your doctor can monitor your bone health before, during, and after breast cancer treatment with a bone mineral density test called a DEXA or DXA scan. This test will show whether you're at risk for osteoporosis and broken bones.

Your doctor might recommend that you get a DEXA scan before you start treatment as a baseline measurement for comparison later. Then, if you do lose bone density, you can start on a medicine to help strengthen your bones.

DEXA scan results come in the form of a T-score, which compares your bone density to the average healthy young adult. A T-score of -2.5 or below in the hip or spine means you have osteoporosis and may need treatment.

If you've lost bone density or are at risk for fractures because of breast cancer treatment or other reasons, your doctor might put you on medicine to prevent or treat osteoporosis. Your doctor can use the FRAX tool, an osteoporosis risk assessment test, to estimate your 10-year fracture risk.

Medications that can help include:

Bisphosphonates. These slow bone loss and reduce fracture risk in the hip and spine. Some examples of bisphosphonates are:

Depending on which medication you get, bisphosphonates come in the form of a pill or an IV infusion.

Denosumab (Prolia). People who can’t take bisphosphonates or don't get a good response from them may try this alternative. You get it through an injection once every 6 months. It also reduces the breakdown of bone tissue.

Raloxifene (Evista). This selective estrogen receptor modulator (SERM) acts like estrogen on your bones. Evista is used to prevent and treat osteoporosis.

These are a few things you can do to help protect your bones and lower your risk for osteoporosis during breast cancer treatment:

Get plenty of calcium and vitamin D. These nutrients strengthen bones. You need 1,000 to 1,200 milligrams of calcium and 800 to 1,000 international units (IU) of vitamin D daily. You'll find them in fortified dairy products, dark green leafy vegetables, and fish. If you don't get enough calcium and vitamin D from food, ask your doctor about adding a supplement.

Do weight-bearing exercises. Putting your own weight on your bones strengthens them. The best bone-building exercises require you to move against the force of gravity. Walking, stair climbing, and playing tennis all fit the bill. Add in strength training with weights, bands, or your own body weight for resistance.

Avoid tobacco and alcohol. Both of these substances weaken bones. Smoking also lowers the amount of calcium your body absorbs from food.

Talk to your doctor about other ways to protect your bones during and after treatment for breast cancer.