While hormone replacement therapy (HRT) can ease menopausal symptoms, such as hot flashes and fatigue, current or recent past users of HRT have a higher risk of being diagnosed with breast cancer.
Before the link between HRT use and breast cancer risk was established, many postmenopausal women took HRT for many years to ease menopausal symptoms and to reduce bone loss. Since 2002, when research linked HRT and risk, the number of women taking HRT has dropped dramatically. Still, many women continue to use HRT to handle bothersome menopausal symptoms.
There are two main types of HRT:
- Combination HRT contains the hormones estrogen and progesterone.
- Estrogen-only HRT contains only estrogen.
Research has found that:
- Breast cancer risk goes up in the first several years of HRT use; risk seems to keep increasing the longer a woman uses HRT.
- Both combination HRT and estrogen-only HRT increase breast cancer risk, but combination HRT increases risk more.
- High-dose HRT increases risk more than low-dose HRT.
The higher breast cancer risk from using HRT is the same for so-called "bioidentical" and "natural" hormones as it is for synthetic hormones. "Bioidentical" means the hormones in the product are identical to the hormones your body produces. Bioidentical hormones are said to be "natural" -- derived from plants. Synthetic hormones are made in a lab and are also chemically identical to the hormones in your body. It's important to know that many herbal and bioidentical HRT products fall outside the jurisdiction of the United States Food and Drug Administration and so aren't subject to the same regulations and testing that medications are.
Menopausal side effects can dramatically reduce quality of life for some women. These women have to weigh the benefits of HRT against the risks. If you're having severe hot flashes or other menopausal side effects and are considering HRT, talk to your doctor about ALL of your options. Ask how you can minimize your breast cancer risk AND relieve your symptoms. Be sure to discuss the pros and cons of different types and doses of HRT.
Research strongly suggests that estrogen-only HRT appears to increase breast cancer risk less than combination HRT. If you do decide to take HRT, ask if you can take a lower-dose formula and talk to your doctor about taking it for the shortest time possible.
If you've been diagnosed with breast cancer or have tested positive for an abnormal breast cancer gene (BRCA1 or BRCA2) and so are at high risk, you shouldn't use HRT. The hormones in HRT can cause hormone-receptor-positive breast cancers to develop and grow. While only a few small studies have looked at HRT use in women with a personal history of breast cancer, the fact that HRT use increases breast cancer risk among women in general makes almost all doctors advise women with a personal history of breast cancer to avoid HRT. The prescribing sheet included with HRT clearly states that it is "contraindicated in women with a diagnosis of breast cancer." Not being able to use HRT can present a challenge for many women. If you're having severe hot flashes or other menopausal side effects and have a personal history of breast cancer, talk to your doctor about non-hormonal options, such as dietary changes, exercise, weight management, acupuncture, or meditation.
For more information on HRT and breast cancer risk, visit the Using HRT page in the Breastcancer.org Lower Your Risk section.