Does estrogen cause cancer?
Estrogen plays a role in causing certain cancers.
Cells in your body have hormone receptors. The hormone receptors are a type of protein. Estrogen in your bloodstream can attach to the receptors. This hormone-receptor process is part of typical body function. In healthy cells, estrogen aids normal cell function and growth.
Today, experts know that several different factors play a role in turning healthy cells cancerous. When these factors are present, estrogen can act as a spark. The hormone causes cancer cells to multiply and spread.
What are the risk factors for estrogen-dependent cancers?
Factors that slightly raise the chance of developing estrogen-dependent cancer include:
- Higher-than-usual estrogen levels.
- Hormone replacement therapy.
- Obesity.
- Polycystic ovary syndrome (PCOS).
- Use of diethylstilbestrol (DES), an artificial estrogen, during pregnancy (between 1938 and 1971) or prenatal exposure to DES.
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What is the link between estrogen and breast cancer?
About 8 out of 10 breast cancers are hormone receptor-positive. These cancers need estrogen, progesterone or both hormones to grow. Excess exposure to estrogen raises cancer risk. Excess exposure can occur because of:
- Hormone replacement therapies for menopause.
- Naturally high estrogen levels.
- Klinefelter syndrome, a genetic condition affecting men.
In the past, some men took estrogen to treat prostate cancer. Healthcare providers rarely use this treatment now because it increases the risk of male breast cancer.
What is the link between estrogen and ovarian cancer?
Longer lifetime exposure to estrogen may heighten your chances of ovarian cancer. Risk factors include:
- Starting menstruation before age 12.
- Never being pregnant.
- Entering menopause after age 55.
- Taking combination hormone therapy (estrogen and progesterone) after menopause.
What is the link between estrogen and uterine cancer?
Uterine, or endometrial, cancer forms in the lining of your uterus. Women are more likely to develop this cancer after menopause.
Your estrogen-related risk may go up with:
- Estrogen replacement therapy: Estrogen eases menopausal symptoms like hot flashes, night sweats and vagin*l dryness. But taking estrogen alone increases the risk of uterine cancer. Combination hormone therapy (estrogen and progesterone) is less likely to cause uterine cancer. If you’ve had a hysterectomy, you don’t have a uterus and can’t get uterine cancer.
- Tamoxifen: Tamoxifen is a breast cancer drug that lowers the risk of breast cancer and breast cancer recurrence. It’s a selective estrogen receptor modulator (SERM) that blocks estrogen’s effects on breast tissue. But in menopausal women, tamoxifen acts like estrogen in your uterus. It stimulates the growth of your uterine lining, increasing endometrial cancer risk. Still, the chances of developing endometrial cancer from tamoxifen are less than 1% per year. There’s also a slightly higher risk of uterine sarcoma, a cancer that forms in uterine muscles or tissues.
