HRT and Breast Cancer: What Doctors Need You to Know

For years, hormone replacement therapy (HRT) was widely prescribed to treat hot flashes, night sweats, and other quality of life-robbing menopause symptoms for as long as a woman might want to take it. Some even suggested that HRT could protect the heart and the bones, which led many to think of it as a potential “fountain of youth.”

But this all changed abruptly in 2002 when the Women’s Health Institute (WHI), a large government-run trial looking at estrogen plus progestin (the two hormones in HRT), was halted early due to an increased risk of breast cancer, heart disease, stroke, and blood clots. This sent shock waves through the medical and menopausal communities, leaving many wondering what, if anything, they could do to alleviate symptoms of menopause.

A chilling effect remained in place for years. While many doctors and patients still have reservations about hormone replacement therapy, low-dose, short-term use is considered safe for many women experiencing menopausal symptoms.

A lot has happened since the estrogen-plus-progestin arm of WHI was halted early and much of this news affects women at risk for breast cancer, says Lila Nachtigall, MD, a professor in the department of Obstetrics and Gynecology at NYU Langone Health in New York. For starters, another arm of the WHI found that the 7,000 women who took estrogen alone without progestin didn’t have an increased risk for breast cancer. Estrogen-only therapy is prescribed for women who’ve had a hysterectomy, because women with a uterus have to take progesterone in addition to estrogen to decrease the risk of uterine cancer.

“This was kind of a shock,” says Dr. Nachtigall. This decreased risk was not considered statistically significant, but it does indicate that estrogen alone does not increase breast cancer risk. Women in the study had all aged, and this finding suggests that aging may be the greatest risk factor for breast cancer, she says.

Understanding HRT

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During menopause, a woman’s production of the hormone estrogen drops dramatically, causing a constellation of symptoms such as hot flashes, night sweats, sleep issues, mood swings, vaginal dryness, loss of sex drive and skin and hair changes. There are other health risks that peak after menopause. Replacing estrogen can help offset these symptoms, according to the North American Menopause Society (NAMS).

But taking estrogen alone (without a progestin) increases the risk of endometrial cancer in women who still have a uterus, which is why progestin is added to the mix. Research is now looking at other forms, doses, and dosing schedules of progestin that can protect the uterus, but not at the expense of the breast, Dr. Nachtigall says. “We try to use as low of a dose of progestin as we can get away with in women with a uterus.”

NAMS went on record in 2017 to say that HRT is effective for hot flashes, night sweats, and vaginal symptoms and also protect bones; these benefits are most pronounced in women younger than 60 years or who are within 10 years of menopause and have no medical reason not to take extra hormones, the organization notes.

While there is “observational evidence” that hormones won’t affect the risk of breast cancer in women with a family history, says NAMS, there is still a concern: “Estrogen does not initiate breast cancer, but if a breast cancer is estrogen-receptor positive and is already growing but not diagnosed yet, estrogen will make it grow more,” says Dr. Nachtigall.

“If a woman is diagnosed with breast cancer and taking HRT, I would advise her to stop taking the hormones,” says Sarah P. Cate, MD, an assistant professor of Surgery at Icahn School of Medicine at Mount Sinai and Director of Special Surveillance and Breast Program at Mount Sinai Chelsea Downtown in New York City. “Some women are aware of the possible increased risk for developing breast cancer with HRT, but are willing to accept this risk if they enter menopause early and are having severe symptoms,” Dr. Cate says. “Each patient should have a risk assessment with their doctor prior to taking HRT, to see if they are at an elevated risk of breast cancer.” According to the American College of Obstetricians and Gynecologists, doctors should weigh the HRT risks against the benefits. (Check out the everyday habits you can adopt to lower your breast cancer risk.)

Consider non-hormonal alternatives first

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Marisa Weiss, MD, director of Breast Radiation Oncology and Breast Health Outreach at Lankenau Medical Center in Ardmore, Pennsylvania and founder and president of breastcancer.org, says that non-hormonal treatments should be tried first for all women experiencing menopausal symptoms.

For vaginal dryness and pain during intercourse, lubricants or moisturizers may help, she says. Topical estrogen creams may also be an option since they do not seem to increase breast cancer risk, according to the National Cancer Institute.

“For hot flashes, keep ice water by your side, buy cold beads, avoid spicy foods, and dress in light layers that can be easily peeled off,” she suggests. Fans and air conditioners can also be helpful, she adds.

“If a woman’s transition into menopause is really rough and she could use help smoothing over the rocky terrain, a short course of HRT may be reasonable,” Weiss says. “Start low and go slow. Use the lowest dose for the shortest period of time with careful revaluation.”

A review of 58 studies published in The Lancet found that when taken for a year or less, HRT does not seem to increase the risk for breast cancer, she says. But “the longer a woman is on HRT, the higher her risk of breast cancer, and it takes 10 years for this risk to return to baseline.” The risk of breast cancer was higher with combined estrogen-progestin, but it was also increased with estrogen-only HRT, the study showed. These same hormones are used in oral contraceptives, she says. Research suggests that women who take even low doses of birth control could have a small increase in the risk of breast cancer.

“We want to avoid extended use whenever possible,” she says, noting that this advice does not apply to women who have had breast cancer. “If you have a history of breast cancer, HRT is relatively contraindicated.” Also: Don’t be swayed by bio-identical hormones, she warns, which are widely touted as natural alternatives to HRT. “They may well have the same risks as HRT if they are both having hormonal effects in your body,” she says.

But not all experts agree on this: Dr. Nachtigall believes that “if you had breast cancer years ago and subsequent mammograms, breast sonograms, or MRIs are all negative, you could go on estrogen to treat severe menopause symptoms. It is a very individualized decision.” Your best bet is to discuss your options—and your symptoms—with your doctor to decide which course of treatment is best for you.