Estrogen-Dependent Cancers

What is estrogen-dependent cancer?

Estrogen is a hormone (natural chemical) that your body makes. Your blood carries estrogen to cells and tissues throughout your body.

Estrogen plays a vital role in sexual development and reproductive health. But estrogen is also a carcinogen, which means it has the potential to cause cancer.

In estrogen-dependent cancer, estrogen fuels cancer’s growth. You may also hear the terms:

• Estrogen receptor-positive.
• Hormone-dependent.
• Hormone-positive.
• Hormone receptor-positive.
• Hormone-sensitive.

What is estrogen?

You may think of estrogen as a female hormone. The ovaries, part of the female reproductive system, produce most of a woman’s estrogen. But breast tissue and fat cells also make estrogen in all genders.

In women, estrogen and progesterone (another sex hormone) bring on puberty. Estrogen stimulates the growth of breasts and pubic hair. It also regulates menstruation (periods).

In men, estrogen promotes brain development, sexual function and libido.

What are the types of estrogen-dependent cancers?

Estrogen-dependent cancers include:

• Breast cancer.
• Ovarian cancer.
• Uterine cancer.

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.

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 vaginal 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.

How are estrogen-dependent cancers diagnosed?

Your healthcare provider sends tissue samples from a tumor biopsy to a lab. The lab tests the cells in the samples for hormone receptors. A hormone receptor-positive (HR+) result means estrogen, progesterone or both hormones fuel cancer growth.

How are estrogen-dependent cancers treated?

Your healthcare provider needs to know the hormone receptor status of a cancer. Certain treatments are more effective on hormone-positive cancers. These include:

• Aromatase inhibitors that block an enzyme from changing hormones into estrogen. This treatment only works for women who are postmenopausal (no longer make estrogen).
• Hormone therapies that keep your body from making estrogen.
• Tamoxifen and other SERMs that stop hormone receptors from binding to estrogen.
• Surgery to remove your ovaries (oophorectomy) and stop the production of estrogen.

Can the pill lower the risk of estrogen-dependent cancers?

Yes and no. Women who use hormonal birth control, such as the pill, have a slightly higher risk (around 7%) of developing breast cancer.

But taking the pill can lower the risk of:

• Cervical cancer.
• Colorectal cancer.
• Ovarian cancer.
• Uterine cancer.

How can I prevent an estrogen-dependent cancer?

Cancers often develop for no known reason. Still, you can take steps to lower cancer risk.

• Breastfeed, if possible.
• Cut back on alcohol and quit smoking.
• Eat healthy and stay physically active.
• Lose weight, if needed.
• Talk to your healthcare provider about the safest birth control option for you.
• Use combination hormone therapy or nonhormonal treatments to manage menopause symptoms.

What questions should I ask my doctor?

You may want to ask your healthcare provider:

• Is the cancer estrogen-dependent or hormone-receptor-positive?
• What is the best treatment for this type of cancer?
• What are the treatment risks and side effects?
• What changes can I make to protect my health?
• Should I use a different form of birth control?
• Can I use hormone therapy?

A note from Cleveland Clinic

Most of the time, estrogen plays a positive role in healthy body functions. Estrogen-dependent cancers are an exception. In these cancers, estrogen fuels cancer growth. If you develop a cancer that could be hormone-sensitive, your healthcare provider will do tests to find out if it’s related to estrogen. This information helps your healthcare provider select the most effective treatment for you.