What is hormone therapy for cancer?

Hormones are chemical messengers in the body. They are products of glands in the endocrine system. Glands are made up of specialized cells that secrete the hormones, sending signals to other organs and tissues throughout the body. Some cancers feed on hormones and need them to grow. Hormone therapy for cancer works by either lowering the level of hormones or blocking their effects. Both these actions result in the cancer not having the fuel it needs. This can slow or stop the growth of tumors that rely on hormones.

In many cases, hormone therapy means taking medication—either as a pill or injection. However, doctors sometimes recommend removing the gland that makes the hormone.

Hormone therapy is usually part of an overall treatment plan for cancer. Hormone therapy for cancer is technically a type of targeted therapy for cancer because it is selective and does not affect your entire body like chemotherapy drugs. However, cancer specialists refer to it separately than other targeted cancer therapies.

Depending on the cancer and its stage, you may also need surgery, chemotherapy, radiation therapy, or other treatments. In general, doctors typically use hormone therapy in the following ways:

• Before surgery or radiation to shrink the tumor. This is neo-adjuvant therapy.

• After surgery or another main treatment to help keep the cancer from returning. This is adjuvant therapy.

• For metastatic cancer that has spread or returned

When is hormone therapy for cancer used?

Hormone therapy is not effective for every cancer. The cancer must rely on hormones in order for hormone therapy to work. Your doctor may recommend hormone therapy to treat the following cancers:

• Adrenal cancer affects the adrenal glands, which sit on top of your kidneys. They make steroid hormones, including cortisol and aldosterone. This is a rare cancer. Hormone therapy for this cancer does not have an effect on the cancer itself. Instead, it counteracts high levels of adrenal hormones.

• Hormone receptor-positive breast cancer, which means the tumor has receptors for estrogen, progesterone or both. Most breast cancers—about 2 out of 3—are hormone receptor positive. These tumors tend to be less aggressive than hormone receptor-negative ones. Hormone therapy for breast cancer is a common type of breast cancer treatment.

• Ovarian cancer that is a stromal tumor, a rare form of ovarian cancer. Most ovarian cancers are epithelial tumors and will not respond to hormone therapy.

• Prostate cancer affects a man’s prostate gland. It grows in response to male hormones (androgens).

• Thyroid cancer affects the thyroid gland in your neck. It is a fairly common cancer in the United States.

• Uterine cancer affects a woman’s uterus. The most common form occurs in the lining of the uterus, or endometrium.

Who manages hormone therapy for cancer?

Your oncologist will prescribe and manage hormone therapy for cancer treatment. Oncologists specialize in diagnosing, treating and preventing cancer. They coordinate with other members of your cancer care team, including your primary care doctor, surgeon, radiologist, nurses, and social workers. An endocrinologist may also help manage hormone therapy for cancer. An endocrinologist treats hormone imbalances and other problems with the endocrine system. They also treat hormone therapy side effects.

How does hormone therapy work?

All forms of hormone treatment for cancer work to interrupt the message that hormones are sending to the tumor. Hormone therapy either lowers hormone levels or blocks hormone actions. There are three ways this can help:

• Treating cancer. For some cancers, hormone therapy can slow or stop tumor growth and help prevent it from coming back. This is often the case with hormone therapy for breast cancer and prostate cancer.

• Relieving symptoms. Sometimes, hormones will not treat the cancer itself, but they can help reduce its symptoms. Adrenal cancer is an example. These tumors can overproduce adrenal hormones, causing symptoms. Giving hormone therapy can counteract the effects of having too much of these hormones. Hormone therapy can also relieve symptoms of prostate cancer when other treatments are not feasible.

• Preventing cancer. Certain people at high risk for developing cancer may benefit from hormone therapy to prevent it. Hormone treatment for breast cancer prevention is the best example.

Should I be concerned about hormone therapy side effects?

For most forms of hormone therapy, you are likely to experience unwanted side effects. When treatment aims to stop hormone messages to the tumor, it will also change hormone messages throughout your body. This is commonly a problem when treating breast cancer and prostate cancer.

Hormone therapy for breast cancer side effects

Blocking or reducing estrogen and progesterone can cause menopausal side effects. This is a problem for women who have not already gone through menopause. Symptoms can include hot flashes, night sweats, mood swings, and vaginal dryness. Other side effects are possible depending on the specific hormone therapy.

Hormone therapy for prostate cancer side effects

Hormone therapies for prostate cancer mainly work by reducing male hormone production. This can cause menopausal symptoms in men, such as hot flashes and weight gain. Men may also experience erectile dysfunction, loss of libido, and loss of muscle mass or strength.

Talk with your doctor about hormone therapy side effects before starting treatment. This will prepare you for what’s ahead and will help you recognize side effects when they occur. Call your doctor if you have unexpected or severe symptoms.

What can I expect with hormone therapy?

It’s often necessary to take hormone therapy for several years. Knowing this ahead of time is important so you can plan and prepare. If your doctor recommends surgery, such as ovary removal or prostate removal to manage hormone levels, it is generally permanent. This is equally important to know, especially if it will affect your reproductive ability. Talk with your doctor about all your treatment options. Your doctor can help you weigh the risks and benefits and decide on the best course of action for you.