Therapy with Bisphosphonates

Aromatase inhibitors lower the levels of estrogen, a hormone, by stopping an enzyme known as aromatase from changing other hormones into estrogen. Although they can be used in the treatment of breast cancer, they may adversely affect bone health.

As such, for certain groups of women being treated with aromatase inhibitors, it is recommended that they are also given a class of drugs known as bisphosphonates as these drugs help to preserve bone health.

A bone mineral density (BMD) test measures the amount of calcium and other minerals in your bones. A low score is an indirect indicator of a high risk of bone disease and bone fractures. If you are planning to start treatment using aromatase inhibitors, your BMD score is important in determining if you need to be given bisphosphonates along with your treatment.

The following table indicates the different management plans recommended for women with certain BMD scores planning to begin aromatase inhibitor treatment.

Bone Mineral Density T score


-2.0 to -1.5

-1.5 to -1.0



Check vitamin D level as vitamin D is essential for bone health. Bisphosphonate therapy is recommended.

Check vitamin D level as vitamin D is essential for bone health.

Screen for BMD every year.

Rescreen for BMD in 1 year.


It remains unclear whether a particular bisphosphonate is superior.



If rescreened BMD >-1.0, screen for BMD every 1 to 2 years.

Bisphosphonates have been reported to reduce the rate of breast cancer recurrences in the bone and improve survival in women who have experienced menopause, but not in premenopausal women.