Bone Loss After Hormone Therapy

This page is for people taking hormone therapy for breast or prostate cancer. It explains why these drugs can thin bone, how bone loss is checked, and what helps.

Hormone therapy treats cancers that use hormones to grow, mainly breast and prostate cancer. The National Cancer Institute describes two ways these drugs work. Some "block the body's ability to produce hormones." Others "interfere with how hormones behave in the body."

Estrogen and testosterone also help keep the skeleton strong. So lowering them has an effect on bone. The American Cancer Society states it plainly. Hormone therapy for breast or prostate cancer "can lower hormone levels that contribute to bone mass and density."

NCI lists "weakened bones" among the common side effects of hormone therapy in men. Its prostate cancer hormone therapy fact sheet is more specific. It names "loss of bone density" and "bone fractures." It also notes that "the risk of side effects increases the longer a person is on hormone therapy."

Hormone therapy is not the only cancer treatment that thins bone. ACS also lists certain chemotherapy drugs. It lists treatments that bring on early menopause too, such as surgery for ovarian cancer. NCI's late effects page adds chemotherapy, steroids, and radiation as causes of bone loss that can appear after treatment ends.

Mostly, it feels like nothing. Bone loss is silent until something breaks, or until the spine changes shape. ACS lists the signs worth reporting. They are back pain, "unusual loss of height over time," a "stooped posture or curved upper back," and bones that fracture after a minor injury. A wrist or hip that breaks from a low fall is not a normal part of aging on treatment. It is information your team needs.

There is nothing to feel, so testing is how this gets tracked. ACS says bone density is measured with a "DEXA (dual energy X-ray absorptiometry) scan, also called a bone density scan." Results come in three bands: normal bone density, "low bone density (osteopenia)," and "very low bone density (osteoporosis)."

There are several things you and your team can do.

Calcium and vitamin D. ACS cites NIH amounts. They are 600 to 800 international units of vitamin D per day, and 1,000 to 1,200 mg of calcium per day. Ask your team what applies to you before adding supplements.

Weight-bearing movement. ACS names walking, dancing, stair climbing, and tai chi as low-impact weight-bearing exercise. It explains why they help twice over. Activity "triggers the body to make cells that form bone." It also "builds strong muscles, which can help your balance." NCI's prostate fact sheet says exercise "may help reduce some of the side effects of hormone therapy, including bone loss, muscle loss, weight gain, fatigue, and insulin resistance."

Not smoking, and limiting alcohol. NCI's late effects guidance lists the everyday steps that protect bone after treatment. Avoid tobacco. Eat foods rich in calcium and vitamin D. Do weight-bearing exercise. And limit alcohol.

Bone medicines, for some people. NCI says doctors may prescribe bisphosphonates such as zoledronic acid or alendronate. They may also prescribe denosumab. These drugs "increase bone mineral density in men who are undergoing hormone therapy." ACS adds pamidronate to the bisphosphonate list.

Preventing falls. ACS is blunt: "Falling is the main cause of fractures for people with osteoporosis." It flags risks you can act on: poor footwear, vision problems, clutter, and medicines that cause drowsiness.

Bisphosphonates and denosumab carry a rare risk. NCI calls it "a rare but serious side effect called osteonecrosis of the jaw." ACS says your doctor may suggest seeing a dentist before these medicines start. If dental treatment is likely, raise it before the bone medicine starts, not after.

Tell your cancer care team about back pain, height loss, or a change in the curve of your upper back. Tell them about any bone that breaks from a minor injury. And if you are on a bone medicine, tell your dentist and your oncology team about planned extractions or implants.

These sources do not set a same-day call rule for bone loss itself. So ask your team for theirs. A suspected broken bone is a separate matter. Call your care team right away. For emergencies call 911 or go to the ER.

• Does my specific hormone therapy lower bone density, and by how much is known?
• Should I have a DEXA scan before I start, and how often after that?
• What were my last results, and were they normal, osteopenia, or osteoporosis?
• Do I need a calcium or vitamin D supplement, and at what dose?
• Am I a candidate for a bisphosphonate or denosumab?
• Do I need dental work done before a bone medicine starts?
• What exercise is safe for me, and is anything off limits?

• National Cancer Institute, Hormone Therapy to Treat Cancer
• National Cancer Institute, Hormone Therapy for Prostate Cancer
• National Cancer Institute, Late Effects of Cancer Treatment
• American Cancer Society, Osteoporosis

Helpful next pages include Side Effects of Cancer Treatment, Immune-Related Side Effects, Low White Blood Cells During Chemotherapy, and Supportive Care.