Estrogen, Bone Loss, and Chemotherapy

How the cancer treatment can cause loss of bone density

Osteodensitometry of the hip with an osteoporosis
Osteodensitometry of the hip with an osteoporosis. Getty Images/BSIP/UIG

If you've recently finished chemotherapy for breast cancer, you might want to ask your family doctor or your oncologist to send you for a bone density scan. This is a painless test that will show whether your bones have lost density or thinned during your treatments due to lower levels of estrogen, a hormone produced by the ovaries that helps build and protect your bones.

How Chemo Can Cause Bone Thinning

Chemotherapy that includes the combination of cyclophosphamide, methotrexate, and fluorouracil (CMF) is the most likely cause of estrogen suppression. Post-chemo medications, such as Tamoxifen and Raloxifene, also help to lower estrogen levels and are important as a follow-up for patients who had estrogen-receptor positive (ER+) tumors.
Estrogen levels drop naturally during menopause and also during chemotherapy, with many pre-menopausal women experiencing "chemo-pause" (ceased or irregular monthly periods). Regardless of whether your estrogen levels drop due to natural or chemical menopause, bone health becomes important to discuss with your healthcare team.

Actions You Can Take After Treatment

You can ask for a blood test which can determine your estrogen levels after you've completed treatment for breast cancer. However, the results may vary greatly, depending on your age, your general health, and how much time has passed since your treatment was completed. Ovaries produce estrogen, and it may take 6 months or more for the ovaries to recover if they're going to be as productive as before treatment. Discuss the timing of the test with your gynecologist or family doctor to get the most accurate results.

If your ovaries do start working again (producing estrogen, stimulating monthly periods), then your bones can regain their natural density and strength on their own. If you're indeed in menopause—haven't had a period in 12 months, a pregnancy test yields a negative result, and you have an elevated level of follicle-stimulating hormone—then you may need to take medication to rebuild bone.

You can also help your body strengthen your bones by adding calcium (both animal and plant-based sourced) with vitamin D to your daily multivitamin, along with weight-bearing exercise. Tai Chi is a great, gentle way to exercise and regain your balance and bone strength. Walking, or using a treadmill or stair machine will also help. If you're up to it, take low-impact exercise classes to help you regain your strength, stamina, and confidence. Remember to drink plenty of fluids and eat a balanced diet, all of which will assist you to the best recovery.

More Tips to Help Your Bones

Smoking contributes to osteoporosis (bone density loss) and although it can be hard to quit, you can reduce your risk of recurrence of breast cancer, as well as lower your risk of other cancers. Heavy use of alcohol also causes osteoporosis, as well as causing your body to increase estrogen levels in your blood, so it's best to limit consumption.

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Article Sources

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