Estrogen-Dependent Cancers

Estrogen-dependent cancers use the female estrogen hormone to grow and possibly spread. Estrogen doesn’t cause cancer. But it can make some cancerous cells grow more quickly. This happens when estrogen attaches to proteins (receptors) in cancerous cells.

Breast, ovarian and uterine (endometrial) cancers are examples of estrogen-dependent cancers. Oncologists treat these cancers with hormone therapy that keeps estrogen away from cancerous cells.

Breast cancer is the most common example. Estrogen plays a role in several types, including:

• ER-positive (ER+) breast cancer
• HR positive (HR+) breast cancer
• Luminal A breast cancer
• Luminal B breast cancer
• Triple positive breast cancer

What causes estrogen-dependent cancer?

This type of cancer happens when estrogen attaches to cancerous cells in certain parts of your body. Some cells in your body have proteins (hormone receptors). Estrogen in your bloodstream can attach to the proteins. In healthy cells, estrogen that attaches to proteins helps those cells work and grow. In estrogen-dependent cancer, the hormone makes cancerous cells divide and multiply.

Risk factors

Long-term exposure to the hormone increases your risk. Long-term exposure may happen if you:

• Start your period before age 12
• Go into menopause after 55
• Take hormone replacement therapy for menopause symptoms
• Take estrogen-only hormonal replacement therapy for a long time, which can increase the risk that ovarian cancer will be estrogen-dependent
• Have estrogen dominance (hormone imbalance)

Other risk factors include:

• Having obesity
• Having polycystic disease

Rarely, taking the cancer drug tamoxifen for breast cancer may increase your risk of estrogen-dependent uterine cancer. Tamoxifen lowers breast cancer risk and treats hormone-positive breast cancer that comes back. But if you’re going through menopause, the drug acts like estrogen and helps uterine cancer grow.

How doctors diagnose this condition

Your healthcare provider or oncologist will do a biopsy to get tissue samples. A lab checks the samples for hormone receptors. A hormone receptor-positive (HR+) result means estrogen, progesterone or both hormones are helping cancer to grow.

Treatment

Hormone therapy for cancer is a common treatment for estrogen-dependent cancer. It works by:

• Blocking cancerous cells’ access to estrogen
• Keeping your body from producing estrogen
• Replacing estrogen with lab-made estrogen (hormone) that cancer can’t use to grow

Your oncologist may use hormone therapy with other treatments, like surgery, chemotherapy or radiation therapy.

Can I reduce my risk by avoiding phytoestrogens?

Researchers are unsure if phytoestrogen affects your risk of estrogen-dependent cancers Phytoestrogens are plant-based foods that act like estrogen. Dairy milk, whole wheat and soy are examples. Research shows that getting estrogen from food may be useful if you have low estrogen levels. It may be a different story if you don’t need extra estrogen.