Bone health during breast cancer treatment can be a concern, but there are ways to reduce the impact. If a person is at risk for a loss of bone density, doctors can prescribe medications.

Lifestyle practices, such as performing weight-bearing exercises and eating a balanced diet, may also promote bone strength.

This article discusses the impact of breast cancer treatment on bone health, how each treatment affects the bones, and to what extent. It also examines how people can manage their bone health during and after treatment and what medications are available to help with this.

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Breast cancer and its treatment can affect bone health in several ways. For example, a 2022 review notes that there is emerging evidence that inflammation due to breast cancer may have a negative effect on bone health. Some of the treatments also affect estrogen levels in the body, which in turn affects bone strength.

Estrogen is a hormone that plays a key role in bone health. A reduction in estrogen causes a higher rate of bone cell turnover, which results in bone loss over time.

For some treatments, this effect is intentional. A 2022 review notes that the majority of breast cancers are estrogen receptor-positive, which means estrogen fuels their growth. Consequently, some treatments reduce estrogen levels to stop this from happening.

But even if the cancer is not estrogen receptor-positive, other treatments can affect estrogen production by the ovaries. For example, some chemotherapy medications can cause bone loss.

As a result, having breast cancer can cause osteopenia and raise the risk of osteoporosis. Osteopenia refers to a reduction in bone mass, while osteoporosis denotes a reduction in bone mass to such an extent that it increases the risk of fractures.

A 2018 study of younger people with breast cancer found that they had a 68% higher risk of osteoporosis and osteopenia than those who had not had breast cancer.

Breast cancer treatments that affect the bones include:

Endocrine therapy

Endocrine therapy for breast cancer involves taking medications that suppress or block estrogen in various ways. This type of treatment can last for up to 10 years, and while effective, it quickly affects bone density.

Examples of this type of treatment include:

  • aromatase inhibitors, such as anastrozole (Arimidex), which prevent the precursors of estrogen from converting to estrogen
  • tamoxifen, which blocks estrogen from reaching breast cancer cells
  • estrogen suppression of the ovaries through surgical removal or gonadotrophin-releasing hormone (GnRH) agonists, such as goserelin (Zoladex)

Sometimes, doctors recommend that those who are not yet experiencing menopause continue endocrine therapy after the cancer is gone to reduce the chances of it coming back.


Chemotherapy kills cancer cells. Although this treatment does not necessarily have the aim of affecting estrogen production, it can cause a complication known as chemotherapy-induced ovarian failure (CIOF). Since the ovaries produce estrogen, CIOF can raise the risk of weakened bones.

Radiation therapy

This uses beams of radiation to kill cancer cells. Radiation exposure increases the risk of bone loss and fractures.

Chemotherapy does not always weaken the bones. Many factors influence the impact of chemotherapy, such as:

  • the type of drugs a person receives
  • age
  • whether the person is pre- or postmenopause
  • their bone density before treatment begins
  • the length of their treatment

Endocrine therapy is more likely to cause bone loss. The extent of this will vary from case to case. For example, tamoxifen slightly raises the risk of osteoporosis in perimenopause, but it actually lowers the risk in postmenopause.

A 2020 review of previous research examines the degree to which other treatments affect the bones. The typical bone loss in postmenopausal individuals who do not have breast cancer is approximately 1–2% per year. In contrast, it is:

  • 2–3% per year for postmenopausal people who take an aromatase inhibitor
  • 7% and 7.7% for premenopausal individuals who take chemotherapy-induced ovarian failure drugs and GnRH agonists, respectively
  • 11% for premenopausal people who take both an aromatase inhibitor and a GnRH agonist

Doctors can prescribe drugs known as bisphosphonates or RANKL inhibitors to manage bone loss in breast cancer.

Bisphosphonates slow the rate at which the body reabsorbs bone, meaning a person loses less bone over time. RANKL inhibitors increase the rate of bone remodeling, which is the natural process the body uses to remove mature bone cells and replace them with new ones.

Doctors may also recommend getting more calcium or vitamin D. Both of these nutrients are important for bone strength. Diet and lifestyle changes may be enough for some people to increase their intake, but others may benefit from supplements.

The National Breast Cancer Foundation recommends the following lifestyle practices for those undergoing treatment:

Weight-bearing exercise

Weight-bearing exercises put stress on the bones, which stimulates the formation of new bone tissue and increases bone strength. People should try to aim for 30 minutes per day to make a substantial difference. Examples of weight-bearing exercises include:

  • walking
  • stair climbing
  • dancing
  • weightlifting

A balanced diet

A generally balanced diet is beneficial during cancer treatment, but protein, calcium, magnesium, and vitamin D are particularly important for bone strength. Sources of protein include:

  • lean meats
  • beans
  • nuts
  • tofu
  • dairy products

People can get calcium from:

  • dairy products
  • fortified foods
  • almonds
  • dark green leafy vegetables

Sources of magnesium include:

  • spinach
  • avocados
  • bananas
  • dark chocolate
  • certain nuts and seeds

For extra vitamin D, people can also try eating more:

  • oily fish
  • fortified foods
  • eggs
  • mushrooms

Sunlight or supplements

Vitamin D helps the body absorb calcium. However, it can be difficult to get enough of it from food alone. One of the main sources of vitamin D is sunlight exposure, but not everyone can get natural sunlight all year round.

When possible, people should aim for 5–30 minutes of sunlight exposure on the skin twice per week. If this is not possible, it may be necessary to take a vitamin D supplement.

Smoking and alcohol

If a person smokes, then quitting may reduce the impact of cancer treatment on bone health. This is because smoking:

  • limits calcium absorption
  • slows the formation of bone-forming cells
  • decreases the protective effect of estrogen
  • reduces blood supply to the bones

Limiting alcohol intake to less than 3 ounces (85 milliliters) per day may also help, as drinking more than this amount speeds up bone loss.

As well as protecting bone health during treatment, it is important to continue doing so afterward. Bone density naturally decreases with age, so continuing these habits can reduce the risk of fractures throughout life.

People who are at risk of fractures may need to keep taking osteoporosis medications after cancer treatment, too. A doctor will be able to advise on this.

Bone health during breast cancer treatment is a common concern because bone loss is a potential side effect of several treatment options, particularly endocrine therapy.

Treatment to manage bone loss can entail taking bisphosphonates or RANKL inhibitors, both of which may strengthen the bones.

Various lifestyle practices may also help. These include engaging in weight-bearing exercises and eating a healthy diet, with a focus on getting adequate vitamin D, calcium, and magnesium.