Hormone Therapy May Still Have Role in Osteoporosis Treatment

Roxanne Nelson

March 18, 2022

Doctors' opinions about whether to treat women with osteoporosis with hormone therapy vary. Guidelines by medical societies including those of the American College of Physicians, on the other hand, generally do not recommend it as a first line therapy for the disease, at least in part due to the risks associated with taking it.

This type of hormone therapy (HT) can be given as estrogen or a combination of hormones including estrogen. The physicians interviewed for this piece who prescribe HT for osteoporosis suggest the benefits outweigh the downsides to its use for some of their patients. But such doctors may be a minority group, suggests Michael R. McClung, MD, founding director of the Oregon Osteoporosis Center, Portland.

According to McClung, HT is now rarely prescribed as treatment — as opposed to prevention — for osteoporosis in the absence of additional benefits such as reducing vasomotor symptoms.

Researchers' findings on HT use in women with osteoporosis are complex. While HT is approved for menopausal prevention of osteoporosis, it is not indicated as a treatment for the disease by the Food and Drug Administration. See the prescribing information for Premarin tablets, which contain a mixture of estrogen hormones, for an example of the FDA's indications and usage for the type of HT addressed in this article.

Women's Health Initiative Findings

The Women's Health Initiative (WHI) hormone therapy trials showed that HT reduces the incidence of all osteoporosis-related fractures in postmenopausal women, even those at low risk of fracture, but osteoporosis-related fractures was not a study endpoint. These trials also revealed that HT was associated with increased risks of cardiovascular and cerebrovascular events, an increased risk of breast cancer, and other adverse health outcomes.

The release of the interim results of the WHI trials in 2002 led to a fair amount of fear and confusion about the use of HT after menopause. After the WHI findings were published, estrogen use dropped dramatically, but for everything, including for vasomotor symptoms and the prevention and treatment of osteoporosis.

Prior to the WHI study, it was very common for hormone therapy to be prescribed as women neared or entered menopause, said Risa Kagan MD, clinical professor of obstetrics, gynecology, and reproductive sciences, University of California, San Francisco.

"When a woman turned 50, that was one of the first things we did — was to put her on hormone therapy. All that changed with the WHI, but now we are coming full circle," noted Kagan, who currently prescribes HT as first line treatment for osteoporosis to some women.

Hormone Therapy's Complex History

HT's ability to reduce bone loss in postmenopausal women is well-documented in many papers, including one published March 8, 2018, in Osteoporosis International, by Kagan and colleagues. This reduced bone loss has been shown to significantly reduce fractures in patients with low bone mass and osteoporosis.

While a growing number of therapies are now available to treat osteoporosis, HT was traditionally viewed as a standard method of preventing fractures in this population. It was also widely used to prevent other types of symptoms associated with the menopause, such as hot flashes, night sweats, and sleep disturbances, and multiple observational studies had demonstrated that its use appeared to reduce the incidence of cardiovascular disease (CVD) in symptomatic menopausal women who initiated HT in early menopause.

Even though the WHI studies were the largest randomized trials ever performed in postmenopausal women, they had notable limitations, according to Kagan.

"The women were older — the average age was 63 years," she said. "And they only investigated one route and one dose of estrogen."

Since then, many different formulations and routes of administration with more favorable safety profiles than what was used in the WHI have become available.

It's both scientifically and clinically unsound to extrapolate the unfavorable risk-benefit profile of HT seen in the WHI trials to all women regardless of age, HT dosage or formulation, or the length of time they're on it, she added.

Today's Use of HT in Women With Osteoporosis

Re-analyses and follow-up studies from the WHI trials, along with data from other studies, have suggested that the benefit-risk profiles of HT are affected by a variety of factors. These include the timing of use in relation to menopause and chronological age and the type of hormone regimen.

"Clinically, many advocate for [hormone therapy] use, especially in the newer younger postmenopausal women to prevent bone loss, but also in younger women who are diagnosed with osteoporosis and then as they get older transition to more bone specific agents," noted Kagan.

"Some advocate preserving bone mass and preventing osteoporosis and even treating the younger newly postmenopausal women who have no contraindications with hormone therapy initially, and then gradually transitioning them to a bone specific agent as they get older and at risk for fracture.

"If a woman is already fractured and/or has very low bone density with no other obvious secondary metabolic reason, we also often advocate anabolic agents for 1-2 years then consider estrogen for maintenance — again, if [there is] no contraindication to using HT," she added.

Thus, an individualized approach is recommended to determine a woman's risk-benefit ratio of HT use based on the absolute risk of adverse effects, Kagan noted.

"Transdermal and low/ultra-low doses of HT, have a favorable risk profile, and are effective in preserving bone mineral density and bone quality in many women," she said.

According to McClung, HT "is most often used for treatment in women in whom hormone therapy was begun for hot flashes and then, when osteoporosis was found later, was simply continued.

"Society guidelines are cautious about recommending hormone therapy for osteoporosis treatment since estrogen is not approved for treatment, despite the clear fracture protection benefit observed in the WHI study," he said. "Since [women in the WHI trials] were not recruited as having osteoporosis, those results do not meet the FDA requirement for treatment approval, namely the reduction in fracture risk in patients with osteoporosis. However, knowing what we know about the salutary skeletal effects of estrogen, many of us do use them in our patients with osteoporosis — although not prescribed for that purpose."

Additional Scenarios When Doctors May Advise HT

"I often recommend — and I think colleagues do as well — that women with recent menopause and menopausal symptoms who also have low bone mineral density or even scores showing osteoporosis see their gynecologist to discuss HT for a few years, perhaps until age 60 if no contraindications, and if it is well tolerated," said Ethel S. Siris, MD, professor of medicine at Columbia University Medical Center in New York.

"Once they stop it we can then give one of our other bone drugs, but it delays the need to start them since on adequate estrogen the bone density should remain stable while they take it," added Siris, an endocrinologist and internist, and director of the Toni Stabile Osteoporosis Center in New York. "They may need a bisphosphonate or another bone drug to further protect them from bone loss and future fracture [after stopping HT]."

Victor L. Roberts, MD, founder of Endocrine Associates of Florida, Lake Mary, pointed out that women now have many options for treatment of osteoporosis.

"If a woman is in early menopause and is having other symptoms, then estrogen is warranted," he said. "If she has osteoporosis, then it's a bonus."

"We have better agents that are bone specific," for a patient who presents with osteoporosis and no other symptoms, he said.

"If a woman is intolerant of alendronate or other similar drugs, or chooses not to have an injectable, then estrogen or a SERM [selective estrogen receptor modulator] would be an option."

Roberts added that HT would be more of a niche drug.

"It has a role and documented benefit and works," he said. "There is good scientific data for the use of estrogen."

Dr Kagan is a consultant for Pfizer, Therapeutics MD, and Amgen and is on the Medical and Scientific Advisory Board of American Bone Health. The other experts interviewed for this piece reported no conflicts.

This story originally appeared on MDedge.com, part of the Medscape Professional Network.

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