Author: Virginia Leach
Is There a Link Between Bone Health and Breast Cancer?
Osteoporosis is a condition in which bones become weak and brittle. Those who have osteoporosis are at a higher risk of developing bone fractures. Many factors affect osteoporosis risk, including diet, exercise, and genetics.
Hormone levels play a role in osteoporosis risk as well. Estrogen is one such hormone, and higher levels have reduced bone breakdown. Conversely, when estrogen levels decrease, bone breakdown can increase. While some bone breakdown is normal and natural, too much breakdown with insufficient rebuilding can result in osteoporosis and put you at a higher risk of bone fractures.
The breasts and the bones are both estrogen-sensitive organs. Therefore, more estrogen exposure means less risk for osteoporosis. However, more estrogen in the blood may also indicate an increased risk of breast cancer, specifically in women after menopause. Additionally, higher lifetime exposure to estrogen may increase breast cancer risk.
Due to the estrogen link, higher bone mineral density (BMD) is associated with a higher risk of breast cancer.
Hormone Positive (HR+) Breast Cancer and Bone Loss
According to the University of Pennsylvania’s Abramson Cancer Center, HR+ breast cancer can be determined when breast cancer cells have receptors for either progesterone or estrogen. From their research, almost 80% of all HR+ breast cancers are positive for estrogen receptors (ER+) or form a combination of positive progesterone receptors (PR+) and estrogen receptors (ER+).
HR+ breast cancer operates differently from other types of breast cancer on bone loss. As a result, oncologists will often include hormone therapy in treatment care plans to block or lower the number of hormones in the body. This treatment, in particular, can increase the risk of bone loss.
Antiestrogen Therapies: Aromatase Inhibitors and Tamoxifen
Antiestrogen therapies block hormone actions or lower hormone levels in the body. Two such therapies, aromatase inhibitors and tamoxifen, have been shown to negatively affect bone health in women.
Aromatase inhibitors (such as anastrozole, letrozole and exemestane) reduce the amount of estrogen in the body, which can help with breast cancer outcomes. Unfortunately, it can also reduce bone density. Since these drugs block the conversion of androgen to estrogen, estrogen levels in the body are decreased. As mentioned previously, lower estrogen levels often mean reduced bone mineral density. In the case of aromatase inhibitor use, it has been reported that bone fracture risk is increased, and bone loss is accelerated.
Tamoxifen is another antiestrogen therapy that blocks estrogen from attaching to hormone receptors. Since breast cancer cells need estrogen hormones to grow, this obstruction helps slow or stop cancer growth in some instances. Tamoxifen’s effects on bone health depend on whether a woman is premenopausal or postmenopausal. Data suggests this drug has an opposite effect depending on the stage of life. The effects tamoxifen has on bone health depends on whether a woman is premenopausal or postmenopausal, as data suggests this drug has an opposite effect depending on the stage of life. In postmenopausal women, tamoxifen appears to protect against bone loss. In contrast, it seems to decrease bone mineral density in premenopausal women.
What You Can Do to Love Your Bones When Undergoing Breast Cancer Treatment
While specific common breast cancer treatments have been shown to result in positive outcomes, unfortunately, many come with the side-effect of taking a toll on bone health.
It is wise to support bone health before and during treatment (if possible) to maximize bone density when possible. This includes steps like:
- Limit or avoid alcohol
- Participating in weight-bearing exercise
- Avoiding cigarette smoking
- Reducing caffeine intake
- Healthy diet and exercise lifestyle choices
- Good wellness habits such as adequate sleep and stress-reducing activities
- Consuming sufficient calcium, magnesium, phosphorus, and other bone-building nutrients
Bone health can be compromised when treating breast cancer, depending on the care plan. Supporting bone health before, during, and after treatment is a wise step to reduce your risk of struggling with bone health issues later in life, like fractures or an osteoporosis diagnosis. Simple steps can have an enormous impact when it comes to bone health.
The American Cancer Society medical and editorial content team. “Hormone Therapy for Breast Cancer.” The American Cancer Society, 27 October 2021. https://www.cancer.org/cancer/breast-cancer/treatment/hormone-therapy-for-breast-cancer.html.
Cancer Research UK. “Osteoporosis Risk and Hormone Therapy.” Cancer Research UK, 27 January 2021. https://www.cancerresearchuk.org/about-cancer/cancer-in-general/treatment/hormone-therapy/osteoporosis.
Tigerlily Foundation. “Bone Health and You.” Tigerlily Foundation, n.d. https://www.tigerlilyfoundation.org/bone-health-and-you/.
Tigerlily Foundation. “Pure Cat Initiative.” Tigerlily Foundation, n.d. https://www.tigerlilyfoundation.org/programs/pure-cat-initiative/.
University of Pennsylvania Abramson Cancer Center. “Hormone Positive Breast Cancer.” University of Pennsylvania Abramson Cancer Center, n.d. https://www.pennmedicine.org/cancer/types-of-cancer/breast-cancer/types-of-breast-cancer/hormone-positive-breast-cancer#:~:text=Breast%20cancer%20cells%20that%20have,are%20ER%2B%20or%20ER%2FPR%2B.
Zlatopolsky, Ashley. “Antiestrogen Therapy for Breast Cancer.” Healthline, 12 August 2021. https://www.healthline.com/health/breast-cancer/anti-estrogen-therapy