3. Menopause Hormone Therapy (MHT/HRT): Principles and Prescribing
Pedagogy: This lesson uses risk-benefit communication training — building the skill of presenting absolute risk data, debunking myths, and supporting shared decision-making using NICE discussion aids.
Learning Objectives
- Present the absolute risk data for breast cancer with combined and oestrogen-only HRT using NICE/MHRA figures
- Explain the cardiovascular evidence: what the WHI showed, what the 'window of opportunity' hypothesis means, and why NICE says not to use HRT for CVD prevention
- Communicate VTE and stroke risk by route of administration
- Apply the NICE HRT discussion aid in a consultation
Key Facts
Breast Cancer Risk: Absolute Numbers
| HRT Type | Baseline (no HRT) | Extra cases: 5 yrs use | Extra cases: 10 yrs use |
|---|---|---|---|
| Combined HRT | 59/1,000 | +20 (total 79) | +33 (total 92) |
| Oestrogen-only | 59/1,000 | +10 (total 69) | +12 (total 71) |
Per 1,000 women aged 50-69, over 20 years. Source: MHRA/NICE NG23 Discussion Aid 2024.
Key context: postmenopausal obesity and consumption of 2+ units alcohol/day are associated with GREATER breast cancer risk than 5 years of combined HRT (BMS 2026).
Cardiovascular Disease
NICE NG23 (2024): "Do not offer combined or oestrogen-only HRT for primary or secondary prevention of CVD." NICE found no statistically significant subgroup differences in RCT evidence for CVD. The isolated reduced risk in women aged 50-59 starting oestrogen-only HRT was not significant across subgroups. The menopause consultation should be used as a CVD risk assessment opportunity, not a CVD treatment (1,2).
VTE Risk by Route
Background risk: 1.7/1,000 women over 50. Oral HRT: modest increase (greatest in first 12 months). Transdermal HRT: no VTE increase (1). Micronised progesterone is VTE-neutral; synthetic progestins increase risk (2).
Stroke Risk
Baseline risk in women under 60: very low (3/1,000 over 5 years). Transdermal oestrogen: unlikely to increase stroke risk. Oral oestrogen: risk increases with dose, duration, and age at initiation (1).
Life Expectancy and Dementia
NICE NG23: HRT is unlikely to affect overall life expectancy. The WHO-commissioned review (Melville et al., 2025; n=1,016,055) found no association between MHT and dementia risk. HRT should NOT be prescribed for dementia prevention or longevity (1,3).
Clinical Pearl When counselling about breast cancer risk, ALWAYS use absolute numbers (per 1,000 over 20 years), not relative risks. This is the single most important communication skill in menopause prescribing.
Clinical Pearl The three HRT myths: (1) HRT prevents heart disease — NO (NICE 2024); (2) HRT prevents dementia — NO (Melville 2025); (3) HRT helps you live longer — NO (NICE 2024). HRT is for SYMPTOM RELIEF and QUALITY of life.
Case-Based Examples
Case 1: Patient frightened by breast cancer risk after reading a newspaper article
Presentation: A 51-year-old with moderate VMS saw a newspaper headline: 'HRT doubles breast cancer risk.' She is now too frightened to take HRT. She has no family history of breast cancer. BMI 28.
Question: How would you reframe the risk conversation using absolute numbers?
Model Answer: Use the NICE discussion aid. Explain: without HRT, 59 out of 1,000 women aged 50-69 will develop breast cancer over 20 years. With 5 years of combined HRT, that becomes 79 out of 1,000 — an additional 20 cases over 20 YEARS, or roughly 1 additional case per 1,000 per year. Put in context: her risk from BMI 28 and even moderate alcohol intake may exceed this. The newspaper used relative risk ('doubles') which sounds alarming but translates to a small absolute increase. Oestrogen-only HRT (if she had a hysterectomy) carries an even smaller increase. Risk declines after stopping. Use the NICE printed discussion aid to show the visual representation. The decision is hers, but she deserves accurate data.
Case 2: GP colleague asking whether HRT prevents heart disease
Presentation: A GP colleague tells you they prescribe HRT to postmenopausal women 'for cardiovascular protection' based on the Danish Osteoporosis Prevention Study showing a 52% reduction in CVD events.
Question: How would you respond, referencing the guideline positions?
Model Answer: Acknowledge the DOPS finding (HR 0.48 for CVD at 10 years), but explain: this was a small, open-label study. NICE NG23 (2024) explicitly states not to offer HRT for CVD prevention. NICE found no statistically significant subgroup differences in the RCT evidence. The WHI — the largest RCT — showed no overall CVD benefit. NAMS (2022) and ACC (Cho et al., 2023) concur. The correct approach: prescribe HRT for symptoms; use the menopause consultation to calculate QRISK3 and treat CVD risk factors with statins and antihypertensives. HRT is for quality of life, not longevity.
Self-Assessment Questions
PLAB/MLA Absolute breast cancer risk with combined HRT
Approximately how many additional breast cancers per 1,000 women aged 50-69 are associated with 5 years of combined HRT use?
A. 5 additional cases
B. 20 additional cases
C. 50 additional cases
D. 100 additional cases
Answer: B. NICE/MHRA data: baseline 59/1,000; combined HRT for 5 years adds ~20 cases (total 79/1,000) over 20 years.
MRCGP Shared decision-making about HRT continuation
A 62-year-old has been on combined HRT for 11 years. She is well, with no symptoms on stopping attempts. She asks: 'Should I stop now because of the cancer risk?' How do you approach this?
A. Insist she stops immediately as she is over 60
B. Conduct a shared decision-making discussion: review her individual risk profile, explain that breast cancer risk increases with duration but there are no arbitrary time limits, and support her informed choice
C. Tell her there is no risk after age 60
D. Switch to oestrogen-only HRT to eliminate risk
Answer: B. BMS 2026: no arbitrary time limits. Annual review of benefit/risk balance. At 11 years, her attributable breast cancer risk is higher than at 5 years, but the decision is individualised. She may choose to continue if quality of life benefits outweigh risk. Document the shared decision.
Professor NICE vs BMS positions on cardiovascular benefit
Compare and contrast the NICE NG23 and BMS positions on cardiovascular benefit of HRT initiated within the 'window of opportunity.'
A. Both agree HRT prevents CVD
B. NICE found no significant RCT subgroup differences for CVD; BMS acknowledges observational data suggesting early-initiation benefit but agrees HRT should not be prescribed for CVD prevention
C. BMS recommends HRT for CVD prevention
D. There is no disagreement between guidelines
Answer: B. NICE applies strict RCT-evidence hierarchy: no significant subgroup differences. BMS 2026 acknowledges WHI subgroup and DOPS observational data suggesting possible CVD benefit with early initiation but does not recommend prescribing for CVD prevention. The Korean guideline is more permissive. This represents a genuine evidence-practice gap: consistent observational signals vs lack of definitive RCT confirmation. The precision menopause approach resolves this pragmatically: prescribe HRT for symptoms, assess and treat CVD risk factors simultaneously.
Take-Away Messages
- Breast cancer: use absolute numbers — combined HRT for 5 years adds ~20 cases per 1,000 over 20 years
- HRT should NOT be offered for CVD prevention (NICE NG23, 2024) or dementia prevention (Melville et al., 2025)
- HRT is unlikely to affect overall life expectancy (NICE NG23, 2024)
- Transdermal HRT does not increase VTE or stroke risk — oral HRT does
- Postmenopausal obesity and alcohol >2 units/day carry GREATER breast cancer risk than 5 years combined HRT