Osteoporosis and breast cancer

Some treatments for breast cancer can affect your bones, making them weaker and more likely to break. This condition is called osteoporosis. Normally, bone loss happens slowly as we age, but certain cancer treatments can speed up this process. It is important to be aware of how your treatment may affect your bones and what can be done to reduce your risk.¹

Some breast cancer treatments lower oestrogen levels in the body, which is helpful for slowing the growth of the cancer—but oestrogen also helps keep bones strong. Hormone therapies such as aromatase inhibitors or ovarian function suppression can lead to bone loss over time. Chemotherapy can also reduce oestrogen levels by affecting the ovaries. Other treatments, such as high-dose or long-term steroid use, and the removal of both ovaries before menopause, can have a similar effect. Radiotherapy to certain areas, like the spine or pelvis, may weaken bones in the area being treated. However, not all cancer treatments lead to bone loss, and your doctor will let you know if your treatment puts you at risk.²

If your treatment is known to increase the risk of bone loss, your doctor will assess your risk of fractures. This includes looking at your age, body weight, history of smoking, use of steroids, and whether anyone in your family has had a hip fracture. You may also be asked to have a special type of scan called a DXA (dual energy X-ray absorptiometry), which measures your bone mineral density. This helps your doctor determine how strong or thin your bones are.

The result of the DXA scan is given as a “T score.” A score of –1 or higher means your bones are normal. If your score is between –1 and –2.5, it means your bones are thinner than normal (a condition called osteopenia). A score of –2.5 or lower means you have osteoporosis and are at higher risk of bone fracture. Based on this assessment, your doctor may recommend regular follow-up scans and steps to help protect your bones.²

If you are at risk of osteoporosis, your doctor may recommend treatment with a bone-targeted medicine to help strengthen your bones. These medicines work by slowing down the natural breakdown of bone, helping to prevent fractures.

There are two main types of bone-targeted treatments: one involves medicine injected under the skin that blocks a protein responsible for triggering bone loss, while the other includes bisphosphonates – drugs given as tablets or intravenously – that are absorbed by bone cells to help prevent bone breakdown.²

If your treatment increases your risk of bone loss, there are effective options to manage it. With proper assessment and monitoring, your care team can help protect your bone health during and after cancer treatment.

Nutrition to help with osteoporosis

Some breast cancer treatments can reduce your body’s levels of oestrogen, which can increase the risk of bone loss and osteoporosis. To help protect your bones, make sure you are getting enough calcium and vitamin D. Good sources of dietary calcium include dairy products, leafy greens like collard greens, broccoli or turnip greens, dried fruits, and seeds such as sunflower seeds. It is best to obtain calcium from food, as the body can absorb only about 400–500 mg at a time. If your doctor recommends calcium supplements, they will help you choose the right amount and type. Vitamin D is important because it helps your body absorb calcium effectively.²

Exercise for osteoporosis

If you are at risk of osteoporosis due to cancer treatment, regular exercise can help strengthen your bones and reduce the risk of fractures. Weight-bearing exercises—such as walking, jogging, dancing, stair climbing, and weight training—are especially helpful, because they work the bones and muscles against gravity.² The program should include resistance training to strengthen muscles and balance training to help prevent falls. Aerobic exercise is helpful, but it is best not to focus on it alone without also including strength and balance exercises.³ Always talk to your healthcare team before starting new exercises so they can help you choose the safest and most effective plan for you.

Sources

1. ESMO. Breast Cancer: A Guide for Patients. (2018).
2. ESMO. The Patient Guide on Bone Health in Cancer. (2022).
3. Giangregorio, L. M. et al. Too Fit To Fracture: exercise recommendations for individuals with osteoporosis or osteoporotic vertebral fracture. Osteoporos. Int. 25, 821–835 (2014).