Does hormone therapy cause breast cancer? What the evidence says

Key takeaways

• The risk is not the same for every type of hormone therapy. Combined therapy carries more risk than estrogen alone.
• In absolute terms, the British Menopause Society estimates about 7 extra breast cancer diagnoses per 1,000 women using combined therapy for up to 5 years from age 50, against a background of 13 per 1,000 without therapy.
• Risk rises with longer use and decreases after stopping, though some studies show a small excess persisting for years in long-term users.
• Obesity and regular heavier drinking carry a breast cancer risk of a similar size, according to the British Menopause Society.
• In November 2025 the US FDA began removing breast cancer from the boxed warning, but it did not declare hormone therapy risk-free. The decision is still individual.

Why does this question cause so much fear?

See, I'll tell you what happens in my room. I mention hormone therapy, and before I finish the sentence, the woman says, "But Doctor, doesn't it cause cancer?" Sometimes it is her husband who says it. Sometimes her daughter.

For two decades, many women in India were told hormone therapy "causes cancer". That belief comes largely from how the Women's Health Initiative (WHI) study, published around 2002, was reported. The results were widely misinterpreted and applied to every woman, of every age, on every type of therapy. Many women who could have been helped were frightened away, and many doctors stopped prescribing.

The pendulum has since swung. But I will not give you the opposite slogan either. The honest answer is not "hormone therapy does not cause breast cancer". The honest answer is that the risk depends on the type of therapy, how long you take it, and your own background risk. And for many women it is small compared with other factors in their lives.

What do the numbers actually show?

The British Menopause Society's 2025 consensus statement summarises the data for women starting hormone therapy at 50, over five years:

I like to picture this as a hall of 1,000 women, all 50 years old. Over five years, 13 of them would be diagnosed with breast cancer anyway. Put all 1,000 on combined therapy, and observational data suggest about 7 more.

A large 2019 analysis in The Lancet, which pooled worldwide studies, put it another way. If the associations are largely causal, about 1 in 50 women using estrogen plus daily progestogen for five years from age 50 would develop breast cancer because of it, about 1 in 70 with intermittent progestogen, and about 1 in 200 with estrogen alone. That same analysis found vaginal estrogen was not associated with excess risk.

The Menopause Society's 2022 position statement adds that short-term combined therapy does not appreciably increase risk, estrogen alone may even lower it, and observational studies suggest a rare increase with longer durations.

Does the risk go away when you stop?

Mostly, but not entirely in every case. NICE states that any increase is related to how long you take treatment and reduces after stopping. The 2019 Lancet analysis found that among women who used therapy for five years or more, a small excess risk could still be seen ten or more years after stopping. The British Menopause Society notes that past users are not at elevated risk in the short term and that "most women exposed to HRT will not be diagnosed with breast cancer as a result of exposure."

How does this compare with other risks in your life?

This is where perspective helps. The British Menopause Society compared extra breast cancer cases per 1,000 women aged 50 to 59 over five years:

The figures differ slightly from the first table because this comparison uses women aged 50 to 59. The statement concludes that the risk from hormone therapy is less than that from other lifestyle risk factors overall. The point is, none of these numbers are reasons for panic, and none are reasons to be careless. They are reasons to look at your whole picture, not one fear in isolation.

Does the type of progestogen matter?

Possibly. The British Menopause Society notes that in the 2019 analysis, micronised progesterone and dydrogesterone were not linked to increased risk with use up to five years, but that the data are too limited, especially for longer use, to draw firm conclusions. This is an area of ongoing research. It does not mean any type is free of risk, and the choice of progestogen also depends on your bleeding pattern, side effects and how well it protects the womb lining.

What changed with the FDA in November 2025?

On 10 November 2025, the US Department of Health and Human Services announced that the FDA was initiating removal of the broad boxed warnings from menopausal hormone therapy labels, including references to breast cancer, heart disease and probable dementia. The boxed warning about womb cancer with estrogen alone in women who have a womb stays.

The European Menopause and Andropause Society welcomed the decision but warned that removing a label "does not imply that MHT is suitable for every woman" and that treatment must remain individualised, considering age, symptoms, and personal and family risk. That is exactly how I work.

Who needs extra care?

• Women who have had breast cancer. The British Menopause Society advises that systemic hormone therapy is generally not recommended after breast cancer, and is contraindicated in estrogen receptor positive disease. Non-hormonal options come first. See Non-hormonal treatments for hot flushes.
• Women at high risk, for example with a strong family history or a known gene change. NICE advises offering all options and referral to a menopause specialist. Non-hormonal treatments are usually first-line.
• Women with breast lumps or abnormal imaging should have these assessed before starting.

What practical steps should you take if you are considering it?

1. Tell your doctor about any family history of breast or ovarian cancer, including on your father's side. People forget the father's side all the time.
2. Keep up with breast awareness and screening as advised for your age.
3. Ask which type and which progestogen are being suggested, and why.
4. Review the need each year. NICE recommends a review at three months, then yearly.
5. Work on the risks you can change: weight, alcohol and physical activity.

How I approach this at Dr Tvacha

At Cocoon × Dr Tvacha in Thane West, I go through your personal and family history and what these numbers mean for you, not for an average woman in a study. Some women decide hormone therapy is right for them; others choose a non-hormonal route. Both are respected choices, and the decision stays yours. Read about the Right Stop Programme on our women's health page, and see Menopausal hormone therapy explained and Who should not take menopausal hormone therapy?

Written by

Dr Anagha KarkhanisGynaecologist and Fertility Specialist · Reg. No. 2006/02/1187

Leads midlife women's health at Cocoon × Dr Tvacha, Thane.