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How hormonal therapy works

Hormones are substances that regulate specific body functions, such as metabolism, growth and reproduction. They travel in the blood and control the activity or growth of certain cells. For example, the hormones estrogen and testosterone control the growth, development and function of female and male reproductive organs.

Some cancer cells need hormones to grow. For example, some breast cancer cells need estrogen to grow. Cancer cells that need hormones to grow are called hormone dependent.

Hormonal therapy is a cancer treatment that adds, blocks or removes certain hormones to slow or stop the growth of cancer cells that are hormone dependent. Drugs, surgery or radiation therapy to specific organs can be used to change hormone levels. Hormonal therapy affects hormone levels throughout the body, so it is considered a systemic therapy.


Natural hormones are produced by glands or organs in the body. Artificial or synthetic hormones can be made in a lab.

Glands and organs that produce hormones
Gland or organDescriptionHormone produced


small reproductive organs on either side of the uterus (womb), close to the end of the Fallopian tubes

estrogen and progesterone – female hormones involved in reproduction

testicles (testes)

small reproductive organs in the scrotum (the loose skin sac at the base of the penis)

testosterone – male hormone involved in reproduction

pituitary gland

small gland at the base of the brain

luteinizing hormone (LH) – stimulates the testicles and ovaries

adrenocorticotropic hormone (ACTH) – stimulates the adrenal glands

follicle-stimulating hormone (FSH) – stimulates the ovaries and testicles

thyroid-stimulating hormone (TSH) – stimulates the thyroid gland

adrenal glands

small glands above the kidneys

corticosteroids (steroids) – lower the body’s immune response

mineralocorticoids (for example, aldosterone) – help maintain water and electrolyte balance in the body

estrogen (in post-menopausal women)

testosterone (in small amounts) – involved in reproduction


gland located behind and below the stomach

glucagon – raises blood sugar level

insulin – lowers blood sugar level

Hormone treatment

Changing hormone levels in the body can affect cancer cells that are hormone dependent. There are 3 ways to change hormone levels:

  • remove the gland or organ that makes the hormone
  • treat the gland or organ with radiation to destroy hormone-producing cells
  • take hormones or other drugs that interfere with or stop the production of the hormone

Hormone-dependent cancer cells have receptors on their surfaces. Receptors are sites where the hormones attach to the cells and tell them to grow. Certain drugs can block the hormone receptors on the surface of cancer cells. The use of drugs to control or block hormones is called hormonal drug therapy.

Sometimes a sample of the tumour is tested to find out:

  • the type of hormone receptor on the surface of the cancer cells
  • the amount of receptor (hormone receptor level)
  • if hormonal therapy is likely to be effective

Generally, the higher the hormone receptor level (positive test), the more responsive the tumour will be to hormonal drug therapy. If there are no receptors or very few receptors on the cancer cells (negative test), hormones will probably not affect cancer cell growth and other cancer therapies may be more effective. Breast cancer tumours are most commonly tested for estrogen (ER) and progesterone (PR) receptors. Although there are tests for other receptors involved in other types of cancer, measuring them is not part of current practice.

Goals of hormonal therapy

Hormonal therapy may be used for early stage, advanced or metastatic cancers that are sensitive to changes in hormone levels (hormone dependent).

Hormonal therapy is an effective treatment for some cancers. Some tumours may respond to hormone treatment at first, but then stop responding (become refractory). The tumours may start growing again and don’t respond to further hormonal therapy. Other tumours may respond to a different hormonal therapy. For example, if a person stops responding to tamoxifen (Nolvadex, Tamofen), a different hormonal drug, such as anastrozole (Arimidex) or letrozole (Femara), may be useful.

Hormonal therapy and other treatments

Hormonal therapy may be used as the first-line therapy (the primary, most common or preferred treatment). It may also be used with other treatments as part of your treatment plan.

  • Hormonal therapy may be used as neoadjuvant therapy. It is given before surgery to shrink the tumour and make it easier to remove. It may also be given before radiation therapy to shrink the tumour so radiation is given to a smaller area.
  • Sometimes hormonal therapy is used as adjuvant therapy. It is given in addition to the primary treatment (such as surgery or radiation therapy) to more effectively treat the cancer and to lower the risk that the cancer will recur (come back).

The side effects of hormonal therapy depend on the type of hormonal therapy used.


The chemical processes in the body that create and use energy. It includes breaking down food and transforming it into energy, eliminating wastes and toxins, breathing, circulating blood and regulating temperature.

Metabolic means referring to or having to do with metabolism, as in metabolic rate.

systemic therapy

Treatment that travels through the bloodstream to reach cells all over the body.

Systemic therapy may be given by injection into a vein or muscle, or by mouth.

Also called systemic treatment.


A specialized organ or group of cells that produces or releases substances (such as hormones, saliva, digestive juices, sweat, tears or milk) to perform different functions in the body.


Any steroid hormone that acts as an anti-inflammatory by reducing swelling and lowering the body’s immune response (the immune system’s reaction to the presence of foreign substances).

Corticosteroids are made by the adrenal gland. They can also be produced in the lab.


A substance in the blood and other body fluids that carries an electric charge. Electrolytes are responsible for the movement of nutrients and wastes into and out of cells to keep body fluids balanced and to allow muscles to function properly.

Examples of electrolytes include calcium, chloride, potassium and sodium.


The time after menopause.

Post-menopausal means referring to or having to do with the time after menopause.


Heather Moyes I encourage every woman – regardless of how young or how old – to be aware of their body

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