Why you might develop osteoporosis

Women who have had breast cancer may be at increased risk of developing osteoporosis: the loss of bone strength, making bones more fragile and prone to fracture.

If you have been diagnosed with breast cancer, you should ask your doctor to check your bone health, especially if you have other risk factors for osteoporosis such as a family history, low calcium intake and/or low vitamin D levels.

Two measures of bone health are important to consider:

• Bone density and whether it is decreasing
• Fracture and whether there has been a fracture or the risk of fracture has increased

Why you might develop osteoporosis

Women with breast cancer have an increased risk of developing osteoporosis because of the treatments used in breast cancer. Treatments can impact directly on oestrogen levels (vital for bone strength), and may also cause ovarian failure in premenopausal women, resulting in a further significant fall in oestrogen and a premature/early menopause.

Aromatase inhibitors

Aromatase inhibitors are prescribed in Australia for postmenopausal women whose breast cancer has spread beyond the breast and lymph nodes. These drugs work by virtually suppressing all oestrogen production in the body.

Studies using one of these drugs known as anastrozole (sold as Arimidex), has shown a loss of bone density at the spine and hip. This effect seems to be more significant in women who are newly menopausal3. There is also a very slightly increased risk of fracture for women taking this medication, although further research is needed in this area.

Treatment

If you have breast cancer and you are diagnosed with osteoporosis, there are specific therapies available, which can treat this condition and your doctor can advise you. It will be important to develop or maintain an exercise plan, which includes weight bearing exercise, and to ensure there is adequate calcium in your diet.

Did you know that some breast cancer treatments can reduce your bone mineral density?

Bone mineral density, or bone density, is a term that refers to the thickness and strength of bone. As oestrogen helps to protect bones, treatments that reduce oestrogen, or stop it from working, can reduce bone density and increase your risk of bone fractures.

Not all breast cancer treatments reduce bone density. The treatments that are known to affect bone density include:

• Hormone therapies, including tamoxifen, Arimidex, Femara and Aromasin
• Chemotherapy when it triggers menopause in younger women.

Checking your bone density

If you are currently on, or about to begin, one of the above treatments it is a good idea to speak with your doctor about your bone health. It’s important to discuss your bone health early on, as most women with lowered bone density do not experience any symptoms. In fact, most women don’t realise their bone density is low until they fracture a bone.

To check your bone density, your doctor may refer you for a bone mineral density test, which is sometimes called a DXA or DEXA test. This test is painless. It measures bone density at the hip and spine using low-dosage X-rays. It is quite different from the bone scans that you may have as part of your breast cancer diagnosis or follow-up.

The cost of a bone mineral density test ranges from $85 to $160. Unfortunately, there is currently no Medicare rebate available for women who require a bone mineral density test because of their breast cancer treatment.

However, you may be eligible for a Medicare rebate if you:

• are 70 years or older
• have a presumed diagnosis of osteoporosis after experiencing one or more bone fractures after minimal trauma
• have experienced menopause for more than six months before the age of 45
• require diagnosis and monitoring of a variety of health conditions, including rheumatoid arthritis
• require a test 12 months after a significant change in treatment for low bone mineral density.

Some clinics will bulk-bill women who are eligible for a Medicare rebate. This means that you should not have an out-of-pocket cost. You can ask your doctor to refer you to a bulk-billing imaging clinic or to write ‘please bulk-bill’ on the referral form.

To find out if you are eligible for a Medicare rebate, and what your out-of-pocket costs may be, ask the imaging clinic before you make the appointment.

Keeping your bones healthy

There are things you can do to help keep your bones healthy:

Diet

Calcium is essential for building and maintaining healthy bones. Eating foods that are high in calcium can help to maintain your bone health.

These foods include:

• dairy foods (milk, cheese and yoghurt),
• fish with edible bones (sardines, herring, and tinned salmon)
• tofu
• almonds and Brazil nuts
• unhulled sesame seeds
• dark green leafy vegetables (broccoli, spinach and bok-choy)
• dried figs and apricots
• kidney beans
• margarine.

Alcohol consumption has been shown to lower bone density. The National Health and Medical Research Council (NHMRC) recommends healthy Australian adults drink no more than two standard drinks a day. Cancer Council Australia recommends people avoid drinking alcohol if possible, or follow the NHMRC recommendation.

In Australia, the ‘one standard drink’ measurement is 10 grams of alcohol. It is important to remember that one serving of alcohol often contains more than 10 grams of alcohol. For example, if you pour yourself a glass of wine and fill the glass, the glass may contain around 150–200 ml of wine, which is equivalent to between 1.5 and 2 standard drinks.

Vitamin D

Vitamin D is important because it helps your body absorb calcium, which in turn promotes bone health.

You can easily increase your Vitamin D levels by:

• spending time in the sun – expose your arms/legs for around 5–10 minutes a day in the warmer months and around 15–20 minutes in the cooler months
• including foods such as oily fish (sardines, herring and mackerel), liver, and egg yolks in your diet. Some margarine, milks and cereals also have small amounts of Vitamin D added.
• taking Vitamin D supplements

If you are concerned about your Vitamin D levels, have a chat with your doctor.

Smoking

Smoking is known to lower bone density. Giving up smoking will improve your bone health, as well as your general health. If you would like to quit smoking, your GP can help you work out a plan that can improve your chances of quitting successfully. The Quitline (13 78 48) offers free phone advice, support and information resources to help you quit.

Exercise

Getting regular exercise is a very effective way of increasing bone density and reducing your risk of bone fracture.

The types of exercises that are helpful include:

• Weight-bearing exercises – in which your body has to bear its own weight, such as walking, jogging, netball, tennis and dancing.
• Resistance training exercises – including free weights and weight machines found in gyms.

The Australian Department of Health and Ageing recommends a total of two-and-a-half hours of exercise every week. BCNA’s Exercise and breast cancer booklet has information on the benefits of exercise, as well as practical strategies to stay motivated. It also includes an exercise diary for you to keep track of your achievements.

Medication

If your breast cancer treatment is known to reduce bone density, your doctor may prescribe a type of drug that helps to strengthen bones and reduce your risk of bone fracture.

Common drugs used to treat low bone density include:

• Fosamax (alendronate): tablets that are usually taken once a day or once a week depending on the dose
• Actonel EC (risedronate): tablets that are usually taken once a day or once a week depending on the dose
• Prolia (denosumab): an injection given below the skin (subcutaneously), usually every six months. It can be given by your GP or general practice nurse.