Exposure to hormones, specifically estrogen, is thought to increase a woman’s risk of developing breast cancer. Throughout life, women are exposed to hormones. From their first menstrual cycle to the onset of menopause, estrogen and progesterone are stimulating normal breast cells. It is this lifetime exposure to ovarian hormones that is believed to put a woman at risk for breast cancer.
Still, it is not clear if estrogen or other hormones cause breast cancer. What is known is that a woman who has begins her menstrual cycle early before age 12, has her first child late after the age of 35 or have had no children, and goes through menopause late, after age 55 has an increased risk of breast cancer. Another potential risk is hormone therapy.
Hormone therapy (HRT)
During menopause, a woman’s body produces much lower amounts of estrogen and progesterone than when she was menstruating. Low levels of estrogen may cause hot flashes, bone loss, vaginal dryness and mood swings. To help lessen these side effects, doctors may prescribe hormone-based drugs (HRT).
Since HRT adds estrogen (and progestin for women who have a uterus) back to your body, many studies have looked for a possible link between the use of HRT and breast cancer. Recent studies have shown that HRT, especially combined estrogen and progestin, can increase the risk of breast cancer.
Although it is still unproven that estrogen directly causes breast cancer, estrogen may help some breast cancer cells grow when the tumor is already resent in a woman’s body. Some doctors are concerned that exposure to estrogen and/or progestin will increase a woman’s risk of breast cancer recurring. Research studies are still looking into this concern.
HRT – Weighing the benefits against the risks
Any woman currently taking or considering HRT should ask her doctor about potential risks and benefits.
Many women have taken HRT to relieve menopausal symptoms and to lower the risk of chronic diseases, like osteoporosis and heart disease. However, there is now strong evidence that most women should not use postmenopausal hormones to try to lower their risk of chronic disease.
On top of this, evidence also suggests that, although women take HRT to simply feel better, hormone use actually does little to increase women’s quality of life in their postmenopausal years, even in women with some significant symptoms, like severe hot flashes. And while hormone use can decrease the risk of some diseases, such benefits are overshadowed by an increase in the risk of other conditions.
For breast cancer survivors, avoiding postmenopausal hormones may be even more important than for the average woman, as survivors are already at higher risk of developing a second breast cancer. Currently, the prudent choice for most breast cancer survivors is to avoid the use of postmenopausal hormones altogether.