fbpx Is Vaginal Estrogen Therapy Safe for Breast Cancer Survivors?
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Pink pills form a female glyph next to open open pill bottle and genetic code.

Is Vaginal Estrogen Therapy Safe for Breast Cancer Survivors?

Research shows this treatment option is underutilized despite proof of its safety and benefits.
Allison Flynn Becker
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Allison Flynn Becker

Vaginal estrogen therapy, a common form of menopausal hormone therapy (MHT) prescribed for perimenopausal and postmenopausal women to treat vaginal dryness, is often underutilized for breast cancer survivors.

Research suggests some forms of exogenous estrogen can increase the risk of cancer and cancer recurrence, while others do not appear to affect risk. Exogenous estrogen is estrogen that is administered as medication, as opposed to endogenous estrogens that are made by the body. Some types of cancer, such as estrogen receptor-positive breast cancer, need estrogen to grow.

Types of MHT include:

  • Estrogen plus progestin pills, used by women who have a uterus
  • Estrogen-only pills, used by women who no longer have a uterus
  • Vaginal estrogen therapy in the form of creams, suppositories and rings
  • Estrogen patches

Studies indicate that MHT pills may increase the risk of breast cancer. It's unknown whether patches increase risk, and studies are currently being conducted. However, vaginal estrogen therapy is considered safe for women who have had breast cancer or are at high risk, according to a joint statement from the North American Menopause Society (NAMS) and the International Society for the Study of Women's Sexual Health (ISSWSH).

Still, the treatment remains underutilized in this population of women. In fact, postmenopausal breast cancer survivors experiencing vaginal dryness and other symptoms are half as likely to be prescribed vaginal estrogen as women who have no history of breast cancer, according to recent research presented at the 2022 annual meeting of the American Urological Association (AUA).

The uses for vaginal estrogen therapy

Vaginal estrogen therapy is often used to help with the vaginal dryness that many women experience during menopause. The lack of vaginal moisture can cause discomfort, especially during sex.

"One of the common symptoms of menopause is vaginal dryness and it generally comes a little bit later in terms of the window of symptoms. Local estrogen can help restore the vaginal tissues," said Mache Seibel, M.D., an OB-GYN and a NAMS-certified menopause practitioner in Newton Centre, Massachusetts.

Vaginal estrogen therapy can also treat urinary tract changes, such as urgency, frequency and bladder infections. Menopausal women are at increased risk of urinary tract infections (UTIs). These symptoms collectively are called genitourinary syndrome of menopause, or GSM.

"Vaginal estrogen therapy is our most effective treatment for women experiencing symptoms of GSM," stated Barb DePree, M.D., an OB-GYN and NAMS-certified menopause practitioner in Holland, Michigan.

This therapy is effective because it specifically targets vulvovaginal and urinary symptoms. Unlike oral forms of hormone replacement therapy or patches, which affect generalized symptoms such as hot flashes and mood changes, vaginal estrogen therapy treats only localized vaginal symptoms.

Using estrogen after breast cancer

The concern about using estrogen therapy after breast cancer is that it could potentially promote the growth or increase the recurrence of breast cancer, because most breast cancers contain estrogen receptors.

"Many of the prescription estrogens on the market are considered systemic," DePree said. "They are very consistently avoided in women who've had breast cancer, especially in estrogen receptor-positive breast cancer."

Concern about estrogen therapy causing breast cancer was based on the results of a faulty study, according to Seibel. Estrogen can't cause cancer cells to appear, but it can stimulate cancer cells once they've already appeared.

"Estrogen, once the cancer has started, can stimulate breast cancer cells. So, generally, women who have a history of breast cancer are not given estrogen after that. In other words, it may not initiate it, but if it's there, it could stimulate it," he explained.

Vaginal estrogen therapy, on the other hand, is generally considered safe in women after breast cancer because of its localized effects.

"The majority of vaginal estrogen therapy stays local. There are small amounts that can get into the bloodstream, but it's very nominal," Seibel said.

Still, many physicians are hesitant to prescribe any form of estrogen to women after breast cancer, despite medical guidelines that state vaginal estrogen therapy is safe.

Recommendations for breast cancer survivors

Women who have had breast cancer should start by talking to their OB-GYN and oncologist if they're thinking about starting vaginal estrogen therapy.

"At least 70 percent of our breast cancer survivors are going to have some future symptoms related to GSM," DePree said.

This means most women need some form of treatment for genitourinary symptoms after breast cancer.

"Women early in the process of menopause having bothersome symptoms might use over-the-counter lubricants and moisturizers, but those really don't reverse the progression of it," DePree explained.

Unfortunately, many women find that their OB-GYN and oncologist are not on the same page. An oncologist may advise you to avoid all forms of estrogen, while an OB-GYN may say vaginal estrogen therapy is safe.

"I think we do sometimes put patients in an uncomfortable situation when a gynecologist is saying, 'Yes, it's OK for you to take that,' and an oncologist is saying, 'No, I prefer you not take that,'" DePree said.

These opposing views can make for a difficult decision. For women receiving mixed messages, it can help to get a second opinion or look at the recommendations given by menopause experts, such as NAMS.

In her own private practice, DePree said she prescribes vaginal estrogen therapy to breast cancer survivors.

"There's more and more data coming out all the time looking at the use of this category of products in breast cancer survivors, and the consistent message we see is safety in use," she concluded.