Breast cancer

Hormonal therapy

Breast cancer

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Some breast cancers can be affected by hormones, which are chemicals produced by the body. Hormonal therapy is a way of treating these cancers.

Not all breast cancers can be treated with hormonal therapy.

What you need to know

What are hormones?

Hormones are chemicals that are produced by glands in the body. They travel in the bloodstream to tissues and organs in different parts of the body. They can affect how some cells grow and reproduce.

The body produces several different hormones. Each hormone only affects certain cells. These cells have receptors for that hormone.

What are hormone-sensitive breast cancers?

Some breast cancers have receptors for the female hormones, oestrogen or progesterone. They can have receptors for just one hormone or both of them. Hormones attach to the receptors and make the cancer grow.

These cancers are called hormone-sensitive breast cancers.

Hormonal therapy for breast cancer

Hormonal therapy is a way of treating hormone-sensitive cancers. They either:

  • stop the body from making the hormone, or
  • stop the hormone from affecting the cancer cells.

Hormonal therapy for breast cancer works by:

  • blocking the effect of oestrogen on the cancer cells, e.g.Tamoxifen
  • reducing the amount of oestrogen produced by the ovaries, e.g. surgical removal or drug treatment
  • reducing the amount of oestrogen produced by other parts of the body (not the ovaries), e.g. aromatase inhibitors, like anastrazole (Arimadex), exemestane (Aromasin) and letrozole (Femara).

Hormonal therapy for breast cancer is given for different reasons. They can be used:

  • in hormone-sensitive early breast cancer to reduce the chance of the cancer coming back
  • in hormone-sensitive advanced cancer to slow the growth or spread of the cancer. 

What to ask or talk about

Side effects of hormonal therapy for breast cancer

Some of the common side effects of hormonal therapy for breast cancer are described below.

Hormonal therapy that blocks the effects of oestrogen, e.g. tamoxifen, can cause:

  • hot flushes
  • weight gain
  • problems sleeping
  • feeling sick (nausea)
  • changes in mood, e.g. depression
  • vaginal dryness in women
  • reduced sex drive (libido).

Hormonal therapy with aromatase inhibitors, e.g. anastrazole, can cause:

  • bone or joint pain
  • bone thinning or osteoporosis.

Some hormonal therapy may affect a person’s fertility. If this is a concern for you, talk to your doctor about it. For more information, you may also want to read our section on Fertility issues.

Ask your doctor or nurse what side effects to expect and how to manage them.

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