Breast Cancer in the Family? A Guide to Safe Hormone Therapy

Navigating menopause can bring a whirlwind of changes, and hormone therapy (HT) is a powerful tool to alleviate many symptoms. But if you have a family history of breast cancer, you might be wondering: Is HT safe for me? Let's dive into the research and clear up some confusion.

Understanding the Risk

It's true that hormone therapy has been associated with an increased risk of breast cancer. However, it's important to understand the nuances. Studies show that the type and duration of HT can affect this risk.

It's important to know that estrogen therapy combined with a synthetic progestin (like medroxyprogesterone acetate or norethindrone acetate) is associated with a greater risk of breast cancer compared to estrogen-only therapy (1, 2).

If you have a family history of breast cancer, this risk can feel even more concerning. But here are some important points to know:

According to the Women's Health Initiative, the risk of developing breast cancer attributed to combined HT use is less than 1 additional case per 1,000 users per year (2).
There's no evidence that HT increases the risk of dying from breast cancer, even if you are diagnosed (2, 3).
Age and personal risk factors for breast cancer do not seem to change the risk of getting breast cancer on HT. In other words, HT doesn't seem to add to the risk that comes from age or other risk factors like family history (2).

Personalized Risk Assessment

Deciding whether or not to use HT is a personal choice, and it's crucial to have an individualized risk-benefit evaluation, especially if you have a family history of breast cancer. The Tyrer-Cuzick Breast Cancer Risk Evaluation Tool is a resource that can help estimate your risk (4). Genetic testing can also be helpful to assess risk.

Did You Know? You can discover personalized breast cancer prevention strategies and receive free genetic screening. The WISDOM Study is open to women aged 30-74 without prior breast cancer.

Generally speaking, hormone therapy can be considered in those who have a family history of breast cancer (2). While HT use may have an outsized impact on the risk of developing breast cancer in high-risk patients in theory, the Women's Health Initiative found that the relative risk of breast cancer associated with HT was similar regardless of family history (1, 2, 5).

Types of HT and Risk

The type of hormone therapy matters. Some studies suggest that certain types of HT carry less risk:

Estrogen-only HT may lower the risk of developing breast cancer (2). If you've had a hysterectomy, estrogen-only hormone therapy (HT) may be an option. However, if you have a uterus, you'll need to take a progestogen along with estrogen to prevent thickening of the uterine lining.
Taking estrogen combined with micronized progesterone may also be associated with a lower breast cancer risk compared to combined HT regimens containing synthetic progestins. Specifically, combined therapy with estrogen and micronized progesterone has not been found to increase the risk of breast cancer for up to 5 years (6).
Conjugated estrogens/bazedoxifene (CEE/BZA - brand name Duavee) is another treatment option to consider, and may be considered if you're higher risk, as research has found that CEE/BZA users have a lower risk of breast cancer than those using combined estrogen/progestin hormone therapy (7). In this regimen, the SERM bazedoxifene replaces a progestogen, because it adequately blocks estrogen's effect on the uterine lining.
If you're thinking about using combined hormone therapy with estrogen and a synthetic progestin (either because it's cheaper or you can't tolerate micronized progesterone), it might be safer to use the synthetic progestin for only 10-14 days a month rather than every day (8). You may also consider limited the number of years on this regimen, since the risk of developing breast cancer with combined estrogen/progestin HT use seems to increase beyond 5 years of use (9).

Mitigating Your Risk

While you can't change your family history, there are lifestyle factors you can control to help reduce your overall risk of breast cancer:

It's crucial to keep up with routine breast cancer screening, such as mammograms, particularly if you choose to use HT. Be aware that HT use may increase your breast density, which may in turn affect your screening recommendations.
Maintain a healthy weight: Some research indicates that body mass index can influence breast cancer risk (10).
Limit alcohol: Excessive alcohol consumption is a known risk factor for breast cancer. Of note, the additional risk of breast cancer from combined HT use is similar to the risk from drinking just two alcoholic drinks per day (2)!
Regular physical activity: Exercise has been shown to have a protective effect against breast cancer.
Balanced diet: A diet rich in fruits, vegetables, and whole grains can contribute to overall health and may help reduce cancer risk.

Empowerment Through Knowledge

If you're considering hormone therapy and have a family history of breast cancer, arming yourself with information is key. Talk to your healthcare provider about your individual risk factors, the different types of HT available, and ways to minimize your risk. Together, you can make an informed decision that supports your health and well-being.

References

Huntley C, Torr B, Kavanaugh G, et al. Breast cancer risk assessment for prescription of menopausal hormone therapy in women with a family history of breast cancer: an epidemiological modelling study.
“The 2022 Hormone Therapy Position Statement of The North American Menopause Society” Advisory Panel. The 2022 hormone therapy position statement of The North American Menopause Society. Menopause. 2022;29(7):767-794. doi:10.1097/GME.0000000000002028
Busund M, Ursin G, Lund E, Chen SLF, Rylander C. Menopausal hormone therapy and incidence, mortality, and survival of breast cancer subtypes: a prospective cohort study. Breast Cancer Res. 2024;26(1):151. Published 2024 Nov 4. doi:10.1186/s13058-024-01897-4
Pal Choudhury P, Brook MN, Hurson AN, et al. Comparative validation of the BOADICEA and Tyrer-Cuzick breast cancer risk models incorporating classical risk factors and polygenic risk in a population-based prospective cohort of women of European ancestry. Breast Cancer Res 2021; 23(1): 22.
Hormone Therapy for Postmenopausal Women. Pinkerton JV. The New England Journal of Medicine. 2020;382(5):446-455. doi:10.1056/NEJMcp1714787.
Stute P, Wildt L, Neulen J. The impact of micronized progesterone on breast cancer risk: a systematic review. Climacteric 2018;21:2, 111-122.
Hoffman SR, Governor S, Daniels K, et al. Comparative safety of conjugated estrogens/bazedoxifene versus estrogen/progestin combination hormone therapy among women in the United States: a multidatabase cohort study. Menopause. 2023; 30(8): 824-830.
Different Menopausal Hormone Regimens and Risk of Breast Cancer. Brusselaers N, Tamimi RM, Konings P, et al. Annals of Oncology : Official Journal of the European Society for Medical Oncology. 2018;29(8):1771-1776. doi:10.1093/annonc/mdy212.
Type and Timing of Menopausal Hormone Therapy and Breast Cancer Risk: Individual Participant Meta-Analysis of the Worldwide Epidemiological Evidence. Lancet (London, England). 2019;394(10204):1159-1168. doi:10.1016/S0140-6736(19)31709-X.
Breast Cancer and Lifestyle Factors: Umbrella Review. Hoxha I, Sadiku F, Hoxha L, et al. Hematology/Oncology Clinics of North America. 2024;38(1):137-170. doi:10.1016/j.hoc.2023.07.005.