Hormone replacement therapy (HRT) has been found to increase the risk of breast cancer in some studies. The level of risk can depend on various factors like:
Key Points
- Type of HRT used (estrogen-only vs estrogen plus progestin)
- Duration of HRT use
- Breast cancer type (invasive lobular cancer vs ductal cancer)
- Personal risk factors like family history
Estrogen-Only HRT
Research indicates that estrogen-only HRT, taken for over 5 years, can increase the risk of breast cancer by up to 30%. The risk is lower for shorter duration use.
Estrogen Plus Progestin HRT
Estrogen combined with progestin HRT appears to carry a higher breast cancer risk than estrogen alone. Studies found it elevates risk by up to 75% with over 5 years of use.
Duration of Use
Multiple studies connect extended HRT use with higher breast cancer likelihood:
- Less than 1 year - No appreciable increase in risk
- 1-4 years - Slightly elevated risk
- 5-14 years - Risk increased up to 30% (estrogen-only) or 75% (with progestin)
- 15 years - Risk may decline after stopping but remains elevated
Invasive Lobular Cancer
This less common breast cancer type seems more strongly linked to HRT. Research links 10 years of HRT use to a 2-fold increase in invasive lobular carcinoma risk.
Other Factors
A woman's risk profile impacts how much HRT could increase her personal breast cancer risk. Considerations:
✔️ Family history
✔️ Breast density
✔️ Lifestyle factors
✔️ Genetic markers
Careful screening and risk-benefit analyses with doctors are advised for women considering prolonged HRT. More research is still needed on exactly how much various HRT regimens influence specific breast cancer risks.
