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Breast cancer patients now experience significantly higher survival rates thanks to early diagnosis and more effective treatments. Aromatase inhibitors, a class of hormone therapy medications, stand out as one of the most effective protocols for preventing hormone receptor-positive breast cancer recurrence. While highly effective, these medications can cause bone loss as a side effect. This article explores the connection between aromatase inhibitors and bone loss, their potential to cause osteoporosis or osteopenia, and strategies to protect your bone density while using these medications.
Dr. Theresa Guise, a world-renowned expert on cancer and bone health, shares her insights throughout this article. As a professor, clinician, and chief of the Bone and Mineral Disorder section at the University of Texas MD Anderson Cancer Center, Dr. Guise has dedicated her career to understanding how cancer and its treatments affect the musculoskeletal system.
How Cancer Treatment Impacts Bone Remodeling
Cancer treatments often affect bone health more significantly than cancer itself. While we typically associate cancer’s impact on bones with metastasis (cancer spreading to bone), many cancer treatments can affect bone health even when cancer hasn’t spread to the bones.
Common cancer treatments that can affect bone mineral density include:
- Chemotherapy radiation used across many cancer types
- Anti-estrogen therapy for breast cancer
- Anti-androgen therapy for prostate cancer
- Glucocorticoids (steroid hormones like prednisone or dexamethasone)
These treatments disrupt the bone remodeling process and can lead to bone loss, fractures, muscle weakness, and potentially osteoporosis.
Breast Cancer Treatment and Osteoclasts
Cancer treatments can stimulate osteoclastic bone resorption, accelerating the bone remodeling process. In this situation, osteoclasts destroy bone faster than osteoblasts can rebuild it, resulting in net bone loss.
Breast Cancer Treatment and Osteoblasts
Some treatments, particularly glucocorticoids, directly inhibit osteoblast activity. The effects can be dramatic — radiation therapy, for example, can cause significant bone loss within a short timeframe. This makes it crucial to identify these potential effects before treatment begins and implement preventive measures, such as medications or low intensity vibration therapy.
Aromatase Inhibitors and Bone Loss During Breast Cancer Treatment
As both a researcher and patient, Dr. Guise brings unique insight into aromatase inhibitors, which have become the standard first-line treatment for estrogen receptor-positive breast cancers. These drugs have proven more effective than their predecessor, Tamoxifen, by blocking the aromatase enzyme that converts androgens to estrogens.
While effective at treating breast cancer, aromatase inhibitors reduce estrogen levels below those typically seen in menopausal women, leading to various musculoskeletal problems.
Exercise and Osteoporosis
Exercise is an essential ingredient to bone health. If you have osteoporosis, therapeutic exercise needs to be part of your osteoporosis treatment program.
But what exercises should you do and which ones should you avoid? What exercises build bone and which ones reduce your chance of a fracture? Is Yoga good for your bones? Who should you trust when it comes to exercises for osteoporosis?
A great resource on exercise and osteoporosis is my free, seven day email course called Exercise Recommendations for Osteoporosis. After you provide your email address, you will receive seven consecutive online educational videos on bone health — one lesson each day. You can look at the videos at anytime and as often as you like.
I cover important topics related to osteoporosis exercise including:
- Can exercise reverse osteoporosis?
- Stop the stoop — how to avoid kyphosis and rounded shoulders.
- Key components of an osteoporosis exercise program.
- Key principles of bone building.
- Exercises you should avoid if you have osteoporosis.
- Yoga and osteoporosis — should you practice yoga if you have osteoporosis?
- Core strength and osteoporosis — why is core strength important if you have osteoporosis?
Enter your email address and I will start you on this free course. I do not SPAM or share your email address (or any information) with third parties. You can unsubscribe from my mail list at any time.
Do Aromatase Inhibitors Cause Osteoporosis?
Bone loss affects most women taking aromatase inhibitors. Those starting treatment with osteopenia may develop osteoporosis without preventive measures. This occurs because estrogen naturally inhibits bone-resorbing osteoclasts. When aromatase inhibitors deplete estrogen, bone loss accelerates as osteoblasts struggle to keep pace with increased resorption.
Beyond bone loss from aromatase inhibitors, many postmenopausal women with breast cancer experience muscle weakness and generalized aches in their muscles, bones, and joints. These side effects are associated with aromatase inhibitors and sometimes lead to treatment discontinuation.
Aromatase Inhibitors and Bone Loss: How to Counter Bone Loss
Several strategies can help counter bone loss during aromatase inhibitor therapy:
- Medications like Prolia (denosumab) or bisphosphonates like zoledronate
- Low intensity vibration therapy, particularly helpful for patients experiencing muscle weakness
- Mechanical loading exercises, when tolerated
Research in Dr. Guise’s laboratory shows that low intensity vibration can prevent bone loss, improve muscle strength, and reduce fat in mouse models. A clinical trial at Indiana University is currently evaluating these effects in women taking aromatase inhibitors.
Aromatase Inhibitors and Osteoporosis: Dr. Guise's Personal Journey
Dr. Guise shares her personal experience as a breast cancer patient taking aromatase inhibitors. By combining a low intensity vibration platform (used twice daily) with zoledronate treatment, she achieved a 3% increase in bone density — a marked improvement over the bone loss typically seen with aromatase inhibitors alone.
Aromatase Inhibitors and Bone Loss: Conclusion and Summary
Aromatase inhibitors are an effective treatment for breast cancer. However, they have side effects that patients and clinicians need to address.
There is a relationship between aromatase inhibitors and bone loss, osteoporosis and bone density. Aromatase inhibitors disrupt the bone remodeling process and can lead to a reduction in bone density and cause osteoporosis. In summary:
- Aromatase inhibitors effectively treat estrogen receptor-positive breast cancer but can cause significant bone loss
- Cancer treatments often affect bone health more than cancer itself through various mechanisms
- Without preventive measures, aromatase inhibitors may lead to osteoporosis, especially in patients who already have osteopenia
- Multiple treatment options exist to counter bone loss, including medications and low intensity vibration therapy
- A combined approach using both medication and mechanical stimulation, specifically low intensity vibration, appears most effective at maintaining bone density during treatment
Margaret Martin
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