Hormone therapy

Some types of cancer need hormones to grow. Hormone therapy is a treatment that adds, blocks or removes hormones to slow or stop the growth of cancer cells.

Hormone therapy is sometimes called hormonal therapy or endocrine therapy.

Our bodies produce substances called hormones that are critical to our growth, health and well-being. Natural hormones are made by glands or organs that are part of the endocrine system. This system releases hormones into the blood, which act like messengers between different parts of the body, and control how some cells and organs grow.

The following are some of the endocrine glands and organs that make hormones.

The pituitary gland is a small, pea-sized endocrine gland located at the base of the brain. It releases hormones that control the function of many other hormone-producing glands including:

• the ovaries and testicles
• the adrenal glands
• the thyroid gland

The ovaries are part of the female reproductive system. The ovaries produce eggs and make the sex hormones estrogen and progesterone.

The testicles are part of the male reproductive system. The testicles produce sperm and make the sex hormone testosterone.

The adrenal glands are two endocrine glands, each of which is located on top of a kidney. The hormones they produce control growth, reproduction, sleep, hunger and metabolism. These hormones include:

• aldosterone, which helps the kidneys control the amount of salt in the blood and tissues of the body to help regulate blood pressure
• cortisol, which influences the body’s metabolism, immune system and stress response, by moderating the availability of carbohydrates, protein and fat
• androgens, which regulate the growth, development and function of both the male and female reproductive system
• estrogen, which plays a crucial role in the development and function of the female reproductive system

The thyroid is an endocrine gland located at the front of the neck, just below the larynx (voice box). The hormones it produces, including thyroxine (T4), triiodothyronine (T3) and calcitonin, control the body’s growth, development and metabolism.

The pancreas, located between the stomach and the spine, is a part of both the digestive system and endocrine system. The pancreas produces the following hormones:

• insulin, which lowers the amount of sugar in the blood
• glucagon, which increases the amount of sugar in the blood
• somatostatin, which plays many roles in metabolism and growth in the body, including decreasing the amount of insulin, glucagon, pancreatic enzymes and bile released

Find out more about the endocrine system and hormones.

Normal cells have receptors, which are molecules that hormones can attach to. Once a hormone attaches, they can send signals to the receptors that affect the behaviour or growth of the cells. When cancer cells have these hormone receptors, hormones can cause the cancer cells to grow and divide.

Doctors can treat cancer cells that need hormones to grow with hormone therapy. Hormone therapy works by changing hormone levels in the body to stop or slow the growth of cancer. Hormone levels can be changed by:

• hormone drug therapy, which is taking hormones or other drugs that stop or change the production of the hormone
• removing the gland or organ that makes the hormone

Your doctor may use hormone therapy alone as the main treatment or with other treatments, such as surgery or radiation therapy. You might receive this therapy:

• to shrink a tumour before surgery, making it easier to remove
• to shrink a tumour before radiation therapy so that a smaller area is treated
• after treatment to lower the risk that the cancer will come back

Your healthcare team will explain exactly how you will get hormone therapy and if there is anything you need to do to prepare for it. The team may order hormone receptor tests to see if your cancer type will respond to hormone therapy. Cancer cells that are hormone-receptor positive can be treated with hormone therapy.

Recovery after hormone therapy depends on the type of hormone therapy you have, your general health, how well you tolerated the therapy, and the side effects you experienced. You will have follow-up appointments with your healthcare team. Follow-up appointments are usually scheduled:

• to see how the cancer is responding
• to discuss ways to treat side effects

The type of hormone therapy your doctor will use depends on which type of cancer you have.

Doctors commonly use hormone drug therapy for cancers of the breast, prostate, ovaries and uterus. This therapy works by blocking or changing the level of hormones in the body. Some drugs stop hormone-producing cells from making hormones. Other drugs decrease or increase the amount of hormone produced, which alters its effects on the body.

The type of hormone drug therapy your doctor will choose depends on the type of cancer you have, and your response to treatment. You may take a drug for a specific length of time or for as long as the cancer responds to the treatment. Sometimes, hormone therapy drugs are combined. You will take hormone drug therapy by mouth (orally) or by injection (IV or IM) .

Artificial or synthetic hormones can be made in a lab to be used for hormone therapy.

The following are some types of hormone drug therapies doctors use to treat different cancers.

Corticosteroid (steroid) hormones treat cancers such as lymphoma, leukemia and multiple myeloma. Doctors often combine these drugs with chemotherapy or targeted therapy drugs or both to help the treatment work better. Prednisone, dexamethasone, hydrocortisone and methylprednisone are all members of a class of drugs called corticosteroids.

Thyroid hormones stop the growth of cancer cells after surgery or radiation therapy for thyroid cancer. Doctors also prescribe them to lower the risk that thyroid cancer will come back. Levothyroxine is a thyroid hormone drug.

Somatostatin analogues are a class of lab-made drugs that lower the number of hormones that tumours called neuroendocrine tumours (NETs) make and release. Doctors mainly use these drugs to control symptoms of carcinoid syndrome such as flushing of the skin, pain in the abdomen and diarrhea. Octreotide and lanreotide are 2 types of somatostatin analogue drugs.

Doctors use drugs that block sex hormones to treat cancers that need male or female sex hormones to grow.

• Progestin is a female sex hormone. Doctors use it to treat uterine cancer and breast cancer. Medroxyprogesterone and megestrol are types of progestin drugs.
• Anti-androgens are used to treat prostate cancer. Bicalutamide, flutamide and nilutamide are types of anti-androgen drugs.
• Anti-estrogens include estrogen receptor blockers and selective estrogen receptor modulators (SERMs). Doctors use them to treat breast cancer, uterine cancer and ovarian cancer. Fulvestrant and tamoxifen are types of anti-estrogen drugs.
• Aromatase inhibitors are used to treat breast cancer, uterine cancer and ovarian cancer in those who have gone through menopause. Anastrozole, exemestane and letrozole are types of aromatase inhibitor drugs.
• Luteinizing hormone–releasing hormone (LHRH) agonists are drugs doctors use to treat prostate cancer, uterine cancer and breast cancer. They are also called gonadotropin-releasing hormone (GnRH) agonists. Goserelin, triptorelin and leuprolide are types of LHRH agonist drugs.
• Luteinizing hormone–releasing hormone (LHRH) antagonists are drugs doctors use to treat prostate cancer. They are also called gonadotropin-releasing hormone (GnRH) antagonists. Degarelix and relugolix are types of LHRH antagonist drugs.

For more detailed information on specific drugs, go to sources of drug information.

Surgery to remove glands or organs can stop them from producing hormones. Doctors usually only use surgery as hormone therapy for breast cancer or prostate cancer, but it isn’t common.

An oophorectomy removes the ovaries and lowers the level of estrogen in the body. Doctors may choose this type of surgery to treat breast cancer.

An orchiectomy removes the testicles and lowers the level of testosterone in the body. Doctors may choose this type of surgery to treat prostate cancer and male breast cancer.