Does Hormone Therapy Cause Breast Cancer?
The belief that Hormone Replacement Therapy (HRT) causes breast cancer has persisted since the 1991 Women’s Health Initiative (WHI) study. Unfortunately, this misunderstanding led to widespread fear, discouraging many women from seeking treatment for menopausal symptoms. However, subsequent research and detailed reviews of the WHI data have significantly clarified the risk, showing that the association between HRT and breast cancer is minimal.
Key Insights from Research and Guidelines
Breast Cancer Risk with HRT is Very Low:
According to the 2022 North American Menopause Society (NAMS) Position Statement, the risk of breast cancer from HRT is exceedingly low.
For every 1,000 women using synthetic estrogen and progesterone HRT, fewer than one additional case of breast cancer is reported per year.
Over five years of use, this risk increases slightly to three additional cases per 1,000 women.
Risk Contextualization:
The increased risk from HRT is comparable to everyday factors, such as drinking two alcoholic beverages per day, being overweight, or leading a sedentary lifestyle.
HRT does not appear to increase breast cancer risk for women with a family history of breast cancer, BRCA1 or BRCA2 mutations, or those who have undergone ovary removal.
HRT and Breast Cancer Survivors:
HRT is generally not recommended for breast cancer survivors. However, in cases of severe menopausal symptoms that do not respond to non-hormonal treatments, HRT may be considered in consultation with an oncologist.
Low-dose vaginal estrogen may be an option for managing genitourinary symptoms in survivors but requires detailed discussions with both an oncologist and an HRT provider.
Importance of Breast Cancer Screenings
Regardless of HRT use, regular breast cancer screenings are essential for all women. Screening guidelines vary slightly across organizations:
American Cancer Society (ACS):
Every other year starting at age 40.
Annually starting at age 45.
Every other year after age 55.
American College of Obstetricians and Gynecologists (ACOG):
Screening every 1–2 years starting at age 40 until age 75.
After age 75, screening frequency should be based on individual health and shared decision-making with a healthcare provider.
U.S. Preventive Services Task Force (USPSTF):
Mammograms every other year from age 40 to 74.
Takeaway
The risk of breast cancer associated with HRT is very small, particularly for younger menopausal women. The decision to initiate HRT should be made based on accurate information, personal health needs, and in collaboration with your healthcare provider. Routine breast cancer screenings remain a cornerstone of women’s health, ensuring early detection and better outcomes regardless of HRT use.
Medical Disclaimer
Yes, I’m a women’s health physician, but I am not currently evaluating you in person, do not have your full medical history, and am unable to comprehensively provide adequate medical decision-making on an individual basis. As such, the information I have shared in this document is for educational purposes only and does not replace medical advice from your personal health care provider.
