1. What is osteoporosis?
2. What causes osteoporosis?
3. Breast cancer treatments and bone health
4. How is osteoporosis diagnosed?
5. Do I need a DEXA scan?
6. Fracture risk
7. Looking after your bones
8. Can osteoporosis be prevented or treated?

1. What is osteoporosis?

Osteoporosis is a condition where your bones lose their strength and density. This leads to bones becoming fragile and more likely to break (fracture).

Bones have a thick outer shell and a strong inner mesh filled with collagen (protein), calcium salts and other minerals. The inside looks like a honeycomb, with blood vessels and bone marrow in the spaces between.

Osteoporosis means some of the outer shell and inner structure of the bone become thin. Sometimes the structure starts to break down causing wider spaces, and bones can fracture easily with little or no force. These fractures are often described as ‘fragility fractures’.

image showing normal bone and osteoporosis bone

Generally, osteoporosis causes no pain or symptoms, so often a person won’t realise they have the condition until a fracture happens. The most common sites for a fracture to occur are the wrist, hip and back (spine).

Although osteoporosis cannot be cured, treatments are available to try to keep the bones strong and less likely to fracture.

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2. What causes osteoporosis?

Risk factors for osteoporosis include:

  • getting older
  • oestrogen levels
  • other factors such as your family and medical history

Age

Our bones increase in density and strength until we reach our late 20s. Around the age of 35 we start to lose bone density as part of the natural ageing process. This happens gradually over time but is much more significant after the menopause. A large reduction in bone density is known as osteoporosis. About half the population will have osteoporosis by the age of 75.  

Low oestrogen levels

The hormone oestrogen protects against bone loss and helps to keep bones strong. Women who have gone through the menopause are at increased risk of osteoporosis and fractures because their ovaries no longer produce oestrogen (small amounts of oestrogen are still produced by fat cells).

Women may also have low levels of the hormone oestrogen because of:

  • an early natural menopause (before the age of 45)
  • an oophorectomy (surgical removal of the ovaries) with or without a hysterectomy (surgery to remove the womb)
  • treatment for cancer (such as chemotherapy, hormone therapy or ovarian suppression)
  • the eating disorder anorexia nervosa

Other risk factors

Other risk factors for osteoporosis include:

  • a family history of osteoporosis or hip fracture
  • previous wrist, spine or hip fracture resulting from little or no trauma
  • medical conditions such as Crohn’s disease, coeliac disease, ulcerative colitis, overactive thyroid (hyperthyroidism) and diabetes
  • medication (usually long-term use) including corticosteroid tablets (for conditions such as arthritis and asthma) and anticonvulsants (for conditions such as epilepsy)
  • some antidepressants
  • conditions that leave you immobile for a long time
  • low body weight

Certain lifestyle factors can make you more likely to have low bone density, such as regularly drinking more than the recommended amount of alcohol, smoking or a diet that is low in calcium and vitamin D.

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3. Breast cancer treatments and bone health

Some breast cancer treatments can lower bone density and increase the risk of osteoporosis in both premenopausal women (women who haven’t yet gone through the menopause) and postmenopausal women (women who have gone through the menopause):

  • chemotherapy
  • ovarian suppression
  • tamoxifen
  • aromatase inhibitors

Chemotherapy

Chemotherapy can affect the function of the ovaries, causing an early menopause in some women. This means less oestrogen is produced, which can reduce bone density.

Women aged 45 or under whose periods have stopped for at least a year as a result of treatment may also be at risk of osteoporosis, even if their periods restart.

Some research has shown that postmenopausal women who have chemotherapy may a have greater loss of bone density than they would have had without chemotherapy.

Ovarian suppression

Ovarian suppression is when the ovaries are removed, or temporarily or permanently stopped from working. This means there’s less oestrogen in the body to help the cancer to grow. However, having less oestrogen in the body can also reduce bone density.

Tamoxifen

Tamoxifen blocks the effect of oestrogen on cancer cells.

In premenopausal women, taking tamoxifen may cause a slight reduction in bone density. This is unlikely to lead to osteoporosis unless ovarian suppression is given as well. However, your risk may be higher if you’re 45 or under and your periods have stopped for at least a year.

In postmenopausal women, taking tamoxifen slows down bone loss and can reduce the risk of osteoporosis.

Aromatase inhibitors

Aromatase inhibitors (such as anastrozole, letrozole and exemestane) reduce the amount of oestrogen in the body, which can reduce bone density.

They are mainly used to treat breast cancer in postmenopausal women, but some premenopausal women take an aromatase inhibitor at the same time as having ovarian suppression. Having these two treatments together can reduce bone density.

The likelihood of developing osteoporosis while taking aromatase inhibitors also depends on how healthy your bones were before your breast cancer treatment.

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4. How is osteoporosis diagnosed?

Osteoporosis is usually diagnosed using a bone density scan, often referred to as a DEXA (dual energy x-ray absorptiometry) or DXA scan. A DEXA scan is used to measure bone mineral density (BMD). BMD is the amount of calcium and other minerals in an area of bone and is a measurement of bone strength. The lower your BMD, the more likely osteoporosis will be diagnosed.

A DEXA scan uses a very small amount of radiation, and is quick and painless. While you are lying down, an x-ray scanner will pass over your body taking pictures of your hips and sometimes lower spine. Your results will include a T score. The T score measures how your BMD compares to a range of young healthy adults with average BMD.

The BMD score ranges:

  • T score above -1 is normal
  • T score between -1 and -2.5 is classified as osteopenia (see below)
  • T score below -2.5 is defined as osteoporosis

Find out more about DEXA scans on the Royal Osteoporosis Society website.

If you are found to have osteoporosis, you will be advised about any appropriate drug treatment. You will also be given guidance on any changes to your diet or lifestyle that may be helpful.

Osteopenia

Some people’s results may show they have decreased bone density, but not enough to be classed as osteoporosis. This is called osteopenia. If you have osteopenia you will be given advice about changes you can make to your lifestyle, such as diet and exercise. You won’t usually need treatment, but your doctor will discuss this with you.

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5. Do I need a DEXA scan?

If your treatment team has a concern about your risk of developing osteoporosis they may suggest a DEXA scan to check your BMD before you start treatment.

Your treatment team will follow guidance when deciding whether to recommend a DEXA scan. In England and Wales, they follow guidance from NICE (National Institute for Health and Care Excellence) – an independent organisation that produces evidenced-based guidance on effective ways to prevent, diagnose and treat ill health. Scotland and Northern Ireland have similar guidance.

NICE guidance

NICE recommends that people with early invasive breast cancer (cancer that has the potential to spread to other parts of the body) should have a DEXA scan to assess BMD if they are not having bisphosphonate treatment and they:

  • are starting aromatase inhibitor treatment
  • have treatment-induced menopause
  • are starting ovarian suppression therapy

Follow-up DEXA scans may be recommended every two years for some people.

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6. Fracture risk

Research has shown that your risk of breaking a bone (fracture risk) can be assessed more accurately by including other risk factors, such as your age, family history of hip fracture or whether you have had a fracture in the past. When assessing your fracture risk, your doctor will take these factors into account as well as your BMD score.  

Your doctor may use an online fracture risk assessment tool such as FRAX or Qfracture to predict your risk of fracture over a period of time and help decide if you need treatment. These tools are designed for the general population and do not take into account breast cancer treatment. 

You can read more about having a DEXA scan, the FRAX and Qfracture online assessment tools on the Royal Osteoporosis Society website and nhs.uk

Some people are more at risk of fracture than others. The lifestyle changes mentioned below and treatments to strengthen bones can reduce the risk. 

Many fractures are the result of having a fall. If you are over 65 there is simple self-assessment test to identify if you are at risk of falling on the NHS website.

You can read their guide Get up and go: a guide to staying steady.

A cancer centre based in the US has also produced an online educational tool to promote bone health in people who have been treated for breast cancer.

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7. Looking after your bones

Find out how some simple changes to your lifestyle can help keep your bones strong and healthy. 

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8. Can osteoporosis be prevented or treated?

There are a range of ways to prevent and treat osteoporosis:

  • supplements
  • bisphosphonates
  • denosumab
  • raloxifene
  • calcitriol
  • teriparatide

Although osteoporosis cannot be cured, treatments are available to try to stop the bones losing more bone density and to make them less likely to fracture. You will be advised about any appropriate drug treatment and its possible side effects. the Royal Osteoporosis Society has more information on drugs to prevent and treat osteoporosis.

Supplements

Your GP may recommend a calcium and vitamin D supplement. You may be prescribed a tablet that contains both, such as Adcal D3.

Bisphosphonates

Osteoporosis in people who have had breast cancer is most commonly treated with a group of drugs called bisphosphonates. This includes zoledronic acid, risedronate, ibandronate or alendronate. Bisphosphonates help strengthen your bones and reduce your risk of fractures. Bisphosphonates may also be prescribed to protect your bones if you’re taking an aromatase inhibitor (such as exemestane, letrozole or anastrozole).

Bisphosphonates may be used as a treatment to reduce the risk of primary breast cancer spreading. They are also sometimes given as a treatment for secondary breast cancer in the bone. This is not the same as having osteoporosis.

Denosumab

Denosumab is a drug that may be recommended to reduce the risk of fractures. It is given as an injection twice a year and slows down bone loss in osteoporosis. It’s a treatment for postmenopausal women who are unable to take certain bisphosphonates and who have particular fracture risk factors.

Raloxifene

Raloxifene is given for the prevention and treatment of osteoporosis in postmenopausal women. Raloxifene is only prescribed for women who have had breast cancer if they have completed their breast cancer treatment.

Calcitriol

Calcitriol is a form of vitamin D also shown to reduce spine fracture risk in some postmenopausal women with osteoporosis, but it is only used in certain circumstances.

Teriparatide

Teriparatide is also prescribed for osteoporosis but is usually only recommended if someone is unable have bisphosphonates or denosumab. It may be suggested if someone is very high risk of fracture, particularly of the spine.

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Last reviewed: October 2018
Next planned review begins 2020

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