Back July 12, 2017

How to Keep Your Bones Healthy While on an Aromatase Inhibitor

aromatase inhibitor (AI) therapy

Picking up where we left off

In our last blog, we discussed how your aromatase inhibitor (AI) therapy can affect the health of your bones. Hormones within your body help to maintain healthy bone by balancing the processes of bone loss and formation that naturally occur during one’s lifetime. After menopause the amount of estrogen within your body decreases, which may lead to an imbalance in these natural bone processes. Additionally, AI therapies to treat breast cancer can further lower the amounts of estrogen within your body, threatening your bones even more, and may lead to aromatase inhibitor bone loss (AIBL). Although AI therapy has some benefits over Tamoxifen including better outcomes and a lower chance of some serious effects like — uterine cancers and blood clots, women on AI therapy may be more likely to experience bone loss and bone fractures. In fact, a recent study demonstrated that breast cancer patients were more likely to be hospitalized for a bone fracture compared with the general population.1

So you’re probably thinking, how do I get AI therapy and still also protect my bones?

In March of 2017, The Journal of Bone Oncology published a comprehensive literature review identifying many of the advances in management of aromatase inhibitor bone loss (AIBL). This review outlined three possible drug therapies around to help combat aromatase inhibitor bone loss (AIBL): Intravenous (I.V.) Bisphosphonates, Denosumab, and Oral Bisphosphonates. Below we will break down each of these drug therapies by identifying some of their pros and cons to help you have an informed conversation with your doctor about your choices.

Intravenous (I.V.) Bisphosphonates (Common Brand Names: PremierPro Rx Zoledronic Acid®, Reclast®, Zoledronic Acid Novaplus®, Zometa®)

I.V. Bisphosphonates are used to treat bone loss, which may result from certain diseases such as osteoporosis and is also a known side effect of AI therapy.4 In a combined analysis of more than 2,700 post-menopausal women with early stage breast cancer undergoing AI therapy, bisphosphonates increased bone mineral density (BMD) in both the lumbar spine and hips, two sites that are at a high risk for AI-induced fractures.1 However, these studies also showed that for IV bisphosphonates to be effective, treatment must be initiated in a timely fashion. Patients who immediately began IV bisphosphonate treatment gained BMD in their lumbar spine and hip, whereas patients who delayed treatment actually lost BMD. I.V. bisphosphonates show better, tolerability compared to other AIBL treatments. The most commonly reported side effects are mild, such as skin reactions at the I.V. site and minor flu like symptoms. It is important to let your doctor know if you are using other bisphosphonates, digoxin antibiotics, steroids, diuretics, or arthritis medications because these medications can interfere or react with I.V. Bisphosphonates.4 Although less common, I.V. bisphosphonates can also cause osteonecrosis of the jaw (ONJ).1 Patients are recommended to get regular dental exams during treatment.4 I.V. Bisphosphonates tend to be the preferred method of treating AIBL because they are an effective treatment to restore bone mineral density while avoiding serious side effects.1

Oral Bisphosphonates (Common Brand Name: Actonel®, Actelvia®, Binosto®, Fosamax®, Boniva®)

Oral Bisphosphonates are pills used to treat osteoporosis and bone density loss in post-menopausal women.5 Fewer studies have been conducted on oral bisphosphonates versus intravenous bisphosphonates, so less is certain about their abilities to treat AIBL. However, some of the studies that have been conducted do show very promising results. A 2-year trial was conducted on postmenopausal women with hormone receptor positive early breast cancer receiving the breast cancer drug adjuvant anastrozole who also had a moderate risk of fragility fracture. This study found that taking Riserdronate (one type of Oral Bisphosphonates) increased bone mineral density in lumbar spine and hip. Another study tested 303 postmenopausal women with early breast cancer. Patients with both early breast cancer and osteoporosis (bone thinning) received a weekly dosage of 70mg alendronate (another oral bisphosphonate) and showed an average of a 15.6% increase in bone mineral density in the lumbar spine compared to before treatment.1 Although these results seem very promising, oral bisphosphonates do have their drawbacks. One of the main cons is the rigid dosing requirements required for oral bisphosphonates. Patients must fast before and after dosing and remain upright after taking the pills, which may make many patients give up on the treatment. It was found that less than 20% of patients receiving daily oral bisphosphonates took the medication as prescribed over one year, and only 30% for weekly bisphosphonates.1 To make matters worse, not sticking to the treatment has been associated with increased fracture rates. Oral bisphosphonates could can also cause damage to the esophagus, lower calcium in blood, and increase the risk for of thigh bone fracture.6 There are many different types of oral bisphosphonates and ways to take them (Liquid, regular tablet, delayed tablet, fizzy tablet). It is best to talk with your doctor to find which one could work best for you.

Denosumab (Common Brand Names: Prolia®, Xgeva®)

Denosumab is an injectable drug used for treating osteoporosis (defined as lowered bone mineral density and thinning of bones) to help prevent fractures. In a study of more than 3,000 postmenopausal women with hormone receptor positive (ER+ and/or PR+) breast cancer, twice yearly injections (60 mg denosumab) significantly reduced the decreased the incidence of fractures in half compared to women who received a placebo injection.1 Also, denosumab was found to decrease new spinal fractures and the worsening of existing spinal fractures over 3 years. The reduced number of fractures was seen regardless of age or beginning bone mineral density test results.1 One possible serious side effect is osteonecrosis of the jaw.2 Patients prescribed denosumab are recommended to schedule regular dental exams and take antibiotics after dental procedures.3 In addition, stopping denosumab treatment may lead to an increase in multiple spinal fractures. An I.V. bisphosphonates has been suggested after ceasing denosumab treatments to combat this problem.1

What can you do to improve your bone health naturally? It’s easier than you think!

A simple solution for post-menopausal women with AIBL recommended by the Journal of Bone Oncology and the International Osteoporosis Foundation is moderate exercise and adding calcium and vitamin D supplements to your daily diet.1

What to do with this information

You’re on the right path by taking an active role to reduce the risk of the cancer from coming back by taking your AI meds daily. You’re also doing the right thing by educating yourself about how to help keep the side effects of the medicine at bay. Finding the right treatment to help overcome the bone loss caused by aromatase inhibitor therapy can be a difficult process. In this short blog, we’ve attempted to outline some of the benefits and drawbacks of each type of therapy, but it is important to talk to your doctor and ask which treatment may have the greatest benefits and least impact on your quality of life.


  1. Hadji, et al. Management of Aromatase Inhibitor-Associated Bone Loss (AIBL) in postmenopausal women with hormone sensitive breast cancer:Joint position statement of the IOF, CABS, ECTS, IEG,ESCEO, IMS, and SIOG, Journal of Bone Oncology 7 (2017) 1–12, Available online 23 March 2017

NOTE: This material was created by or on behalf of Biotheranostics, Inc. The content, products and services discussed in this material are offered to educate healthcare providers and/or consumers on molecular diagnostic testing performed by Biotheranostics, and should not be considered or used as a substitute for medical advice, diagnosis or treatment of specific medical conditions. The Breast Cancer Index test is not a companion diagnostic cleared or approved by the FDA; and it does not determine whether or not a specific drug will be beneficial to a specific patient. To see BCI Intended Use & Limitations, please visit