What is hormonal therapy?

We all have receptors on breast cells, but not everyone has estrogen receptors on their breast cancer cells. Estrogen sends signals that control cell pathways. Receptors on the surface of breast cancer cells work like satellite dishes. They detect and bring in hormone signals. These signals can direct cells to grow, multiply and repair damage.

If estrogen receptors are found on breast cancer cells, the breast cancer is called estrogen receptor-positive, or ER+. When progesterone receptors are found, the cancer is progesterone receptor-positive or PR+. About two-thirds of breast cancers are hormone receptor-positive, also known as hormone-sensitive. They may be:

• Both ER-positive and PR-positive
• ER-positive only
• PR-positive only

Even if the cancer has only one type of receptor, or tests just slightly positive, studies show hormonal therapy can benefit you.

Hormonal therapy for breast cancer is not the same as estrogen or hormone replacement therapy, also called ERT or HRT, used in menopause. ERT or HRT replaces or puts back hormones. It is not advised for women affected by breast cancer.

How hormonal therapy works

Hormonal therapy for breast cancer blocks estrogen. It interferes with the signals that hormone receptors send to cells. Depending on the type, hormonal therapy may block estrogen receptors, reduce the amount of estrogen made, or lessen the number of hormone receptors.

You may receive hormonal therapy after surgery, chemotherapy or radiation. Or, your doctor may recommend you take hormonal therapy at the same time as other treatment, such as targeted therapies for HER2-positive disease. In some cases, you may take hormonal therapy to shrink tumors before surgery.

Depending on the type of hormonal therapy, you may take it as a pill, as liquid or by injection. Another option is oophorectomy, surgery to remove the ovaries. If you have oophorectomy, you may receive additional hormonal therapy afterward. It is also possible to take medicine that stops the action of the ovaries.

The standard course of hormonal therapy treatment is daily for 5 to 10 years. Be sure to ask your providers how you will receive treatment, how often you will take it and why they recommend each combination. Even though they work in different ways, hormonal therapies have been shown in long-term research to be effective against hormone receptor-positive disease. No matter what other treatments you receive, hormonal therapy can lower the chances breast cancer will come back.

Because hormonal therapy can change the amount of estrogen in your body or the way your ovaries work to produce estrogen, they impact your fertility. If you are premenopausal, talk with your healthcare team about ways to protect fertility while on hormonal therapy.

How do you know if you need hormonal therapy?

Your doctor will recommend hormonal therapy if the cancer tests estrogen receptor-positive, progesterone receptor-positive, or both. If it does, this means the hormones your body naturally makes helps the cancer to grow. Right after diagnosis, you had tests that checked the hormonal status of the cancer cells. You can find the results of those tests in your pathology report.

Which hormonal therapy you get will depend on your menopausal status, or whether you still get your monthly period regularly, get it only sometimes, or have stopped having your period permanently because of age or medicine.

Adjuvant and neoadjuvant hormonal therapy

In early-stage breast cancer, you can receive hormonal therapy either before or after primary therapy with surgery and with chemotherapy or radiation, if these treatments are needed.

When hormonal therapy is given after surgery, it is called adjuvant therapy. It also might be given at the same time you receive another treatment, such as radiation therapy, chemotherapy or trastuzumab (Herceptin).

Some people receive hormonal therapy before surgery, called neoadjuvant therapy. Your doctor may suggest neoadjuvant hormonal therapy if you have a tumor that is too large to be removed with lumpectomy. This may increase the chances you can preserve your breast.

Hormonal therapy side effects

Many people experience side effects from hormonal therapy, though how bad they are and how often they happen differs for each person. Side effects can include:

• hot flashes
• vaginal dryness
• fatigue
• bone thinning or pain
• hair thinning
• nausea
• loss of interest in sex

If you become uncomfortable during treatment, there are many medicines and methods to help you. Let your doctors and nurses know about your concerns before you start treatment. Your team has many options to lessen, manage or stop side effects.