Women's Health June 23, 2026 0 Comments

What Your Doctor Isn’t Telling You About HRT and a Hidden Cancer Threat—Are You at Risk?

Hormone replacement therapy (HRT) is back in the spotlight—again. But this time, it’s not just about easing those pesky menopause symptoms like hot flashes or night sweats. A fresh study has thrown a curveball, hinting that women with longer reproductive spans or those on hormone therapy might have a slightly higher chance of developing thyroid cancer. Wait, what? Before you hit the panic button, remember—this is just an association, not a full-on cause-and-effect revelation. Intrigued? You’re not alone. Let’s unpack what this means for anyone considering HRT and why doctors are urging calm amidst the buzz. Because when it comes to health, being informed beats being alarmed every time. LEARN MORE

4 min read

A new study suggests women with longer reproductive lifespans and those who take hormone therapy may have a higher risk of thyroid cancer.
This effect was even stronger in women who used hormone therapy for five years or more.
Doctors say not to panic just yet—the study shows an association, not a cause-and-effect relationship, so more research is needed.

Hormone replacement therapy (HRT) is suddenly a hot topic again, thanks to data suggesting it can be a safe and effective treatment for menopause symptoms like hot flashes, night sweats, UTIs, vaginal dryness, and more. Emerging research has even suggested that HRT is associated with a lower risk of Alzheimer’s disease and could be linked to stronger bones. But in the latest update, a new study suggests the treatment may be linked to a higher risk of thyroid cancer.

It’s important to stress this now: This is just a link, and it’s still an area of research that’s being explored. However, if you’re on hormone therapy or considering it, it’s fair to have questions about whether this might change your risk profile. Here’s what the latest data says—and what doctors want you to keep in mind.

Meet the experts: Valentina Tarasova, MD, endocrinologist in the Endocrine Oncology Program at Moffitt Cancer Center; Ruthann Devera, MD, ob-gyn at MemorialCare Medical Group in Long Beach, California; Melanie Goldfarb, MD, endocrine surgeon and director of the Center for Endocrine Tumors and Disorders and medical director of Cancer Survivorship at Providence Saint John’s Cancer in Santa Monica, California.

What did the study find?

The study, presented at ENDO 2026, the Endocrine Society’s annual meeting, examined a nationwide, population-based cohort of about 5.7 million women aged 40 years or older from the Korean National Health Insurance Service. These women participated in screenings for breast and cervical cancer between 2010 and 2011, and were followed through 2023.

Researchers found that about 2.4 out of every 1,000 participants per year developed thyroid cancer. Women with a longer reproductive span and those who had used hormone therapy had a higher risk of thyroid cancer. The effect was stronger in women who used hormone therapy for five years or more.

What is thyroid cancer?

Thyroid cancer happens when abnormal cells grow in your thyroid, a butterfly-shaped gland in your neck, according to the National Cancer Institute (NCI). The thyroid produces hormones that regulate how your body uses energy. Thyroid cancer makes up to 2 percent of all new cancer cases and has a five-year survival rate of 98.3 percent, per the NCI.

What are the signs of thyroid cancer?

Early signs and symptoms usually show up as a lump in the neck, says Valentina Tarasova, MD, an endocrinologist in the Endocrine Oncology Program at Moffitt Cancer Center. “Patients may notice a thyroid nodule themselves, detect an enlarged lymph node, or a healthcare provider may identify a thyroid nodule during a physical examination,” she says.

Patients may also have symptoms like trouble swallowing, hoarseness, neck pain, or breathing difficulties, but Dr. Tarasova says these are less common.

How is thyroid cancer treated?

It depends. Typically, thyroid cancer is treated with surgery, says Melanie Goldfarb, MD, endocrine surgeon and director of the Center for Endocrine Tumors and Disorders and medical director of Cancer Survivorship at Providence Saint John’s Cancer in Santa Monica, California. “Today, surgery is the only treatment needed for many patients,” she says.

Those with more advanced cancers or older adults may need to take a radioiodine pill as well. Patients who have had their entire thyroid removed surgically will also need to take a thyroid hormone replacement, Dr. Goldfarb says.

Why might HRT be linked to thyroid cancer?

The reason behind this specific link is still being explored. “Current studies have shown mixed results,” says Dr. Tarasova. “We know that women are diagnosed with thyroid cancer more frequently than men, particularly during their reproductive years, which suggests that sex hormones may play a role in thyroid cancer development.”

Estrogen can also affect thyroid cells, Dr. Tarasova says. “Estrogen may promote cell growth, activate signaling pathways involved in cancer development, increase oxidative stress, and stimulate the formation of new blood vessels that can support tumor growth,” she says. “These biological mechanisms provide a plausible explanation for why hormone exposure could influence thyroid cancer risk.”

But Dr. Tarasova stresses that it’s unlikely that the higher rate of thyroid cancer in women can be explained by hormones alone, and that there may be other factors contributing to the different rates of diagnosis. “Women tend to have more frequent healthcare encounters and undergo more imaging studies, which can lead to the detection of small thyroid cancers that might otherwise have remained unnoticed,” she points out.

What’s the takeaway?

Women on hormone therapy shouldn’t panic, says Ruthann Devera, MD, ob-gyn at MemorialCare Medical Group in Long Beach, California. “At this point, [the findings] show an association, not a direct cause-and-effect relationship,” she says. “Thyroid cancer is more common in women, and hormones may play a role, but it’s likely just one piece of a much larger puzzle that includes genetics, environmental factors, and even differences in healthcare utilization.”

Dr. Tarasova agrees. “The potential risk of thyroid cancer should not be a major factor when deciding whether to start or continue hormone replacement therapy,” she says. “Current evidence suggests that if there is an increased risk, it is likely modest.”

Korin Miller is a freelance writer specializing in general wellness, sexual health and relationships, and lifestyle trends, with work appearing in Men’s Health, Women’s Health, Self, Glamour, and more. She has a master’s degree from American University, lives by the beach, and hopes to own a teacup pig and taco truck one day.

Carina Hsieh, MPH, is the deputy features editor of Women’s Health. She has more than a decade’s worth of experience working in media and has covered everything from beauty, fashion, travel, lifestyle, pets, to health.

She began her career as an intern in the fashion closet at Cosmopolitan where she worked her way up to Senior Sex & Relationships Editor. While covering women’s health there, she discovered her passion for health service journalism and took a break to get her Masters in Public Health. Post-grad school, she worked as a freelance writer and as The Daily Beast’s first Beauty, Health, and Wellness Reporter.

Carina is an alum of the Fashion Institute of Technology and the Yale School of Public Health. She and her French Bulldog, Bao Bao, split their time between Brooklyn and Connecticut. She enjoys reformer Pilates, (slow) running, and smelling the fancy toiletries in boutique fitness class locker rooms.