Breast cancer & bone health

Last updated 13 February 2017 — Last reviewed 15 December 2013

Treatments used for breast cancer can increase the risk of developing osteoporosis. This page discusses how this might happen and provides information on the effects of chemotherapy, Tamoxifen and Aromatase inhibitors on bone. There is also information on the benefits of diet and weight bearing exercise to help with bone strength if you also are being treated for breast cancer.

woman being treated for cancerWomen 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.

Breast cancer treatment Link to osteoporosis Impact in postmenopausal women
Chemotherapy
  • Ovarian failure in premenopausal women causes significant fall in oestrogen leading to bone loss, particularly in the spine
  • Bone loss in the spine in the first 12 months after chemotherapy is approximately 3-4%
  • If ovarian failure does not occur after chemotherapy, bone mineral density tends to remain stable
Chemotherapy given to postmenopausal women does result in loss of bone density.

Medication: Tamoxifen

also sold as:

  • Nolvadex
  • Istubal
  • Valodex
  • Tamoxifen works by partially suppressing the body's production of oestrogen because it has anti-oestrogen effects in the breast but it does not provide enough oestrogen to help the bones of younger women
  • Women who take Tamoxifen may experience a progressive loss of bone from the spine of approximately 1.4% per year[1]

Postmenopausal women with breast cancer who take Tamoxifen:

  • may have an increase in bone mass in the spine of approximately 1.2% per year
  • may have a slightly increased rate of fracture compared to the normal population[2] but more research is needed in this area
 

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 menopausal[3]. 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.

For more information on breast cancer & bone health go to Breast Cancer Network Australia.

References

  1. Powles TJ, Hickish T, Kanis JA, Tidy A, Ashley S. Effect of tamoxifen on bone mineral density measured by dual-energy x-ray absorptiometry in healthy premenopausal and postmenopausal women. J.Clin.Oncol. 1996;14(1):78-84.

  2. Kanis JA, McCloskey EV, Powles T, Paterson AH, Ashley S, Spector T. A high incidence of vertebral fracture in women with breast cancer. Br.J.Cancer 1999;79(7-8):1179-81.

  3. Baum M, Budzar AU, Cuzick J, Forbes J, Houghton JH, Klijn JG et al. Anastrozole alone or in combination with tamoxifen versus tamoxifen alone for adjuvant treatment of postmenopausal women with early breast cancer: first results of the ATAC randomised trial. Lancet 2002;359(9324):2131-9.

This web page is designed to be informative and educational. It is not intended to provide specific medical advice or replace advice from your health practitioner. The information above is based on current medical knowledge, evidence and practice as at December 2013.

Subscribe To our newsletters