Breast Cancer Hormone Therapy

Block the hormones that cause breast cancer cells to grow with these medications.

Most breast cancers are sensitive to hormones such as estrogen and progesterone. Because of this, hormone therapy often plays an important role in breast cancer treatment.

Your team will walk you through the wide array of available breast cancer hormone therapy treatments and clinical trials.

Types of hormone-receptor-positive breast tumors

In some patients, certain hormones -- usually the female hormones estrogen and progesterone -- attach to breast cancer cells and cause them to grow faster. There are two terms you should know:

• Estrogen-positive or estrogen-receptor-positive (ER-positive): Where the cells respond to estrogen
• Progesterone-positive or progesterone-receptor-positive (PR-positive or PgR-positive): Where the cells respond to progesterone

About 70 percent of breast cancer tumors are ER-positive. Most of those cancers also are PgR-positive. Your doctor will identify whether a tumor is hormone-sensitive after a biopsy or surgery to remove a tumor.

Types of breast cancer hormone therapy

Hormone therapy treats breast cancer by delivering drugs to block your body’s production of the hormones that are encouraging breast cancer cells to grow. Many women take hormone therapy for about five years after breast cancer surgery to prevent a recurrence or growth of their cancer.

Types of hormone therapy include:

• Aromatase inhibitor (AI) drugs: These drugs block production of estrogen in the body. We primarily recommend these drugs for postmenopausal women, unless they are combined in premenopausal women with ovarian function-blocking drugs. Examples of AI drugs include anastrozole (Arimidex) exemestane (Aromasin) and letrozole (Femara).
• Gonodotropin-releasing hormone (GnRH) agonists, also known as luteinizing hormone-releasing hormone (LH-RH) agonists: These drugs block ovarian function. The ovaries are the main source of estrogen production in women. Blocking the ovaries’ function minimizes estrogen in the body, which can help minimize the growth of hormone-sensitive breast cancer. Examples of these types of drugs are leuprolide (Lupron) and goserelin (Zoladex).
• Selective estrogen receptor modulator (SERM) drugs: SERMs prevent estrogen from attaching to breast cancer tells. Tamoxifen is the best known among this class of drug.

Some medications also have been approved for preventive use in women at high risk of developing breast cancer. Genetic testing can tell you if you’re at high risk.

Clinical trials for breast cancer hormone therapy

Our breast cancer patients at times have access to clinical trials investigating new hormone therapies that have not yet been approved for broad clinical use.

Talk with your doctor about whether a clinical trial might be right for you.