Breast Cancer in women

Aromatase inhibitors: Arimidex (anastrozole), Aromasin (exemestane) and Femara (letrozole)

Hormonal therapies are treatments which either reduce the levels of hormones in the body or block their effects on cancer cells. They are often given after surgery, radiotherapy and chemotherapy for breast cancer to reduce the chance of the cancer coming back.
Hormonal therapies are only effective in women whose cancer cells have receptors for oestrogen and/or progesterone on their surface. This is known as being oestrogen-receptor positive (ER+) or progesterone-receptor positive (PR+). It means that the breast cancer cells are affected by oestrogen or progesterone. These are female hormones that the body produces naturally and that can stimulate breast cancer cells to grow. When a cancer is removed and the tissue is studied in the laboratory, testing for whether these hormonal receptors are present is one of the checks that is normally done.
There are many different types of hormonal therapy and they work in slightly different ways. Hormonal therapies for breast cancer include the drug tamoxifen which is from a group of medicines known as a SERM (selective oestrogen receptor modulator). These block the effect of oestrogen on tissue receptors. Another family of drugs which act to reduce hormone levels are the medicines known as aromatase inhibitors (these drugs work by blocking the aromatase enzyme which converts androgen hormones into oestrogen and so they reduce the amount of oestrogen in the body). These do not block the effect of oestrogen from your ovaries, and so are only effective in women whose ovaries have stopped making oestrogen – that is after someone has gone through their menopause either naturally or after surgery to remove the ovaries. Other hormonal treatments work by stopping the ovaries from working to produce hormones. This can either be through medical therapy, for example having a medicine called zoladex (goserelin) which switches off the ovary, or through surgical therapy, which would involve removing the ovaries.
Which hormonal therapy is best for each woman depends on several factors, including:
•          A woman’s age
•          whether a woman has had her menopause (change of life)
•          the stage and grade of the cancer
•          which other treatments are being used
We are going to consider women’s experiences of using these medications in the following sections in ‘Hormonal therapy’.
Aromatase inhibitors: Arimidex (anastrozole), Aromasin (exemestane) and Femara (letrozole)
Aromatase inhibitors are used in post-menopausal women. When women go through the menopause, the ovaries stop producing oestrogen. The body still produces a small of oestrogen in fatty tissue. This production is stopped by the aromatase inhibitors. As less oestrogen reaches the cancer cells, they grow more slowly or stop growing altogether. Aromatase inhibitors include Anastrazole (Arimidex), Femara (letrozole) and Aromasin (exemestane). They are all tablets that are taken once a day and may be given over a number of years. Taking aromatase inhibitors for a few years increases the risk of bone thinning (osteoporosis). A bone density scan (DEXA scan) is used to check bone health before starting treatment, and then every 2 years during treatment if any bone thinning is present. Some women may need treatment to protect their bones, usually depending on the results of these scans.

Some of the women we interviewed talked about their experiences of taking Anastrazole (Arimidex).

A few women said they’d switched from tamoxifen to Arimidex because of the side effects they’d had with tamoxifen.

Some women took tamoxifen first for a number of years and then went onto Arimidex either because of side effects or because they went through the menopause.

Aromasin (exemestane) is another example of an aromatase inhibitor.
One of the women we spoke with had been prescribed Aromasin.
Femara (letrozole) is another aromatase inhibitor which women may be prescribed as hormonal therapy when they are post-menopausal.
One woman said she was prescribed Femara after she’d finished taking tamoxifen.

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Last reviewed May 2015.
Last updated May 2015.


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