Hormone therapy

Hormone therapy may also be called endocrine therapy or hormone-blocking therapy.

Some cancers grow in response to particular hormones. These cancers are known as hormone-dependent cancers. They include some types of breast, uterine and prostate cancers. The aim of hormone therapy is the slow or stop the growth of hormone receptor positive cells.

What are hormones?

Hormones are substances that are produced naturally in the body and affect how your body works. They act as messengers carrying information and instructions from one group of cells to another.

Hormones control many of the body’s functions, including how you grow, develop and reproduce. Examples include:

• the female sex hormones oestrogen and progesterone, which control ovulation and menstruation
• the male sex hormone testosterone, which causes the development of the reproductive organs and other sexual characteristics, such as a deep voice and facial hair
• thyroid hormones, including thyroxine, which control the body’s metabolism

What is hormone therapy?

Hormone therapy uses synthetic hormones to block the effect of the body’s natural hormones. The aim is to lower the amount of hormones the tumour receives. This can help reduce the size and slow down the spread of the cancer.

The treatment may be given as tablets you swallow or injections. For some cancers, you may have surgery to remove a part of the body to stop the production of hormones, e.g. your ovaries may be removed to stop the production of oestrogen.

Hormone therapy to treat cancer is not the same thing as hormone replacement therapy (HRT). HRT supplies the body with hormones that it is no longer able to produce naturally and is often used to treat the symptoms of menopause. People who have had their whole thyroid removed will also need hormone replacement therapy as their body no longer produces thyroxine. Learn more about thyroid hormone replacement therapy.

When is hormone therapy given?

Hormone therapy is usually used with other cancer treatments:

• before surgery or radiation therapy to shrink a tumour
• after treatment to reduce the risk of the cancer returning
• to slow the growth of cancer that has spread throughout the body and help manage symptoms

What are the side effects?

Hormone therapy is a systemic treatment, which means it can affect cells throughout the body.

As each hormone in the body has a specific function, altering the balance of hormones in the body can cause side effects. Whether or not you experience side effects, and how severe they are, depends on the type of hormone you are taking, the dose, and how long you take the treatment. Talk to your doctor about the risks and benefits of taking hormone therapy.

Common side effects include tiredness, hot flushes, mood changes, weight gain and sweating. Hormone therapy can also affect the fertility of both women and men, bring on menopause, and have an impact on your sexuality.

Hormone therapy may also cause bones to weaken and break more easily (osteoporosis). Talk to your doctor about having a bone density test or taking medicine to prevent your bones from becoming weak. Regular exercise, eating calcium-rich foods (e.g. yoghurt, milk, tofu, green vegetables) and getting enough vitamin D will also help keep your bones strong.

Hormone therapy for breast cancer

Around 70-80% of breast cancers are sensitive to the hormones oestrogen (ER) or progesterone (PR). This means that these hormones may be helping the cancers grow. These cancers are called hormone receptor positive (ER+ and/or PR+), and they are likely to respond to hormone therapy that blocks oestrogen.

There are different ways to reduce the level of female hormones in the body, including anti-oestrogen drugs, aromatase inhibitors, and ovarian treatments. The choice will depend on your age, the type of breast cancer and − for women − whether you have reached menopause.

Learn more about Hormone therapy for breast cancer.

Hormone therapy for cancer of the uterus

Some cancers of the uterus grow in response to oestrogen.

Hormone treatment may be given if the cancer has spread or if the cancer has come back, particularly if it is a low-grade cancer. It is also sometimes offered in the first instance if surgery is not an option, for example, for women who still want to have children.

The main hormone treatment for oestrogen-dependent uterine cancer is progesterone.

Learn more about Hormone treatment for cancer of the uterus

Androgen deprivation therapy for prostate cancer

Prostate cancer needs testosterone to grow. Testosterone is an androgen (male sex hormone), so hormone therapy for prostate cancer is called androgen-deprivation therapy (ADT).

ADT slows the production of testosterone, which may slow the cancer’s growth or shrink it temporarily. It may be recommended for locally advanced or advanced prostate cancer.

Learn more about androgen deprivation therapy for prostate cancer.

We thank the reviewers of this information:

Prof Declan Murphy, Urologist and Director of Genitourinary Oncology, Peter MacCallum Cancer Centre, VIC; A/Prof Nicholas Wilcken, Director of Medical Oncology, Westmead Hospital Sydney, NSW; Anne Brooks, Consumer; David Hodgson, Consumer.