Risks of Menopause Hormone Therapy

NICE's evidence-based guidance describes an increased breast cancer risk with combined systemic HRT. The increase grows with duration, is greater during current use, and declines after stopping. Some additional risk persists for at least 10 years after use ends.

For estrogen-only HRT, NICE describes very little or no increase in breast cancer risk. Estrogen alone is generally chosen after total hysterectomy. A woman with a uterus usually needs progestogen protection, so the estrogen-only findings cannot simply be applied to her prescription.

NICE reports lower breast cancer risk with sequential combined treatment than with continuous combined treatment, while both carry more risk than no HRT. There is insufficient evidence to establish whether micronized progesterone has a different breast cancer risk from other progestogens. It should not be presented as a proven risk-free choice.

A personal history of breast cancer requires specialist discussion. Bring the diagnosis, receptor information if available, and current cancer medicines. Population estimates for women without previous breast cancer do not answer the question of recurrence.

Oral HRT increases venous thromboembolism risk, meaning a clot in a vein such as a deep vein thrombosis or pulmonary embolism. NICE does not identify an increased VTE risk with transdermal HRT. Transdermal estrogen enters through the skin, using a patch, gel, or spray.

That finding does not remove your underlying clot risk. Previous clots, hereditary clotting disorders, obesity, and other medical circumstances still need assessment. A strong family history or known thrombophilia may warrant specialist advice before treatment.

Stroke risk also differs by route. NICE describes an increase with oral estrogen, influenced by age, dose, and duration, and considers an increase unlikely with transdermal estrogen. For younger women the baseline risk is lower, but a previous stroke needs its own specialist review.

Systemic estrogen stimulates the endometrium, the lining of the uterus. Estrogen without adequate progestogen protection increases endometrial cancer risk. This applies to both oral and transdermal estrogen.

Continuous combined HRT reduces endometrial cancer risk compared with no HRT in NICE's evidence summary. Sequential combined treatment may slightly increase risk, particularly with longer use, fewer progestogen days per cycle, or a higher estrogen dose. The prescription must provide an appropriate amount and duration of progestogen.

Tell the prescriber if you miss progestogen doses or cannot tolerate them. Unscheduled bleeding needs assessment according to its timing, severity, and risk factors. Bleeding beyond the first six months of systemic treatment or three months after a change needs prompt medical review under NICE guidance; heavy or concerning bleeding warrants earlier help.

The Menopause Society describes a generally favorable balance for bothersome symptoms in otherwise healthy women younger than 60 or within 10 years of menopause who have no contraindications. Starting after 60 or more than 10 years after menopause has a less favorable balance because absolute risks of heart disease, stroke, clots, and dementia are higher.

HRT should not be started for prevention of cardiovascular disease or dementia. NICE also notes that dementia risk might increase when combined HRT is first started at age 65 or older. Starting treatment at that age is a different question from continuing a prescription begun earlier.

ACOG advises that systemic treatment is usually not recommended with previous breast or endometrial cancer, stroke, heart attack, blood clots, or liver disease. NICE allows specialist assessment of some complex cardiovascular histories. The appropriate US plan also needs to follow the selected product's contraindications.

The Women's Health Initiative trial published in 2002 studied 16,608 postmenopausal women aged 50 to 79 who had a uterus. It tested one daily oral regimen: conjugated equine estrogens 0.625 mg plus medroxyprogesterone acetate 2.5 mg. The trial stopped after an average 5.2 years.

A person-year is one person's year of follow-up. These are absolute differences in event rates for the study population. They should not be transferred directly to a younger woman taking an estradiol patch and a different progestogen. The study remains important evidence against using that regimen for primary prevention of chronic disease.

Ask for absolute numbers over the same period

A risk discussion is easier to understand when the clinician compares cases in the same number of similar people over the same length of time. Ask which estimate fits your age and regimen, how much uncertainty remains, and how the expected symptom benefit compares.

Estrogen treatment, with or without progestogen, is associated with a small increase in gallbladder disease, with more risk from pills. NICE also describes a very slight increase in ovarian cancer risk with systemic HRT. These risks belong in the overall review, particularly when there is relevant personal history.

Low-dose vaginal estrogen has much lower systemic exposure and should have its own assessment. NICE describes serious adverse effects as very rare. With previous breast cancer, the effect of any absorbed estrogen on recurrence remains uncertain, so nonhormonal options and the cancer treatment plan should be discussed.

• Confirm the exact estrogen route and whether progestogen is needed.
• Review new diagnoses, medicines, and family-history information at follow-up.
• Use the lowest effective dose and keep recommended screening up to date.
• Report unexpected bleeding or new concerning symptoms promptly.