Breast Cancer in women

Tamoxifen

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’.
 
Tamoxifen
 
Here women we interviewed talk about their experiences of tamoxifen, a hormonal therapy known as an anti-oestrogen drug. Tamoxifen works by preventing oestrogen in the body from attaching to breast cancer cells and encouraging them to grow so it lowers the risk of breast cancer coming back (recurring) after treatment. It can also help to reduce the risk of cancer in the other breast by 40% (Cancer Research UK 2014). It can be used for women who have had their menopause and also for those who haven’t and it can also be used for men with breast cancer. Tamoxifen comes as tablets and is usually given for five years, but some women may benefit from taking it for longer (usually 10 years), but taking tamoxifen for longer is a balancing act as although it reduces the risk of breast cancer coming back it can also increase the risk of womb cancer or DVT’s (deep vein thrombosis- blood clots). This is a decision the individual woman would normally make with her breast cancer specialist.
 
Many women explained why they were prescribed tamoxifen, and discussed the benefits of taking it. A few women had to stop taking HRT (hormone replacement therapy containing oestrogen and progestin given to women in the menopause) when diagnosed with breast cancer, and were given tamoxifen. One woman explained why, initially, she was averse to taking these tablets.

Although a few women had no side effects with tamoxifen, most experienced some symptoms. Hot flushes or sweats were common and sometimes they interrupted sleep. A few women suggested taking evening primrose oil, but there is no scientific evidence of its value for this.

Some women said they gained weight while they were taking tamoxifen. Other women complained of tiredness, and a few had irregular periods. Uterine complications affected a few women. Women who have taken tamoxifen over a long period of time have an increased risk of womb cancer (endometrial cancer). Abnormal vaginal bleeding can be an early sign, so it is very important to get any unusual, changing or post-menopausal bleeding checked straight away by your GP. When womb cancer is found early, treatment is very successful. Mood swings, panic attacks, nausea, insomnia, indigestion, and aches in the bones were some of the side effects experienced by people we talked to. Verite said she had a rare side effect, temporary blindness in one eye, and problems with her skin.

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Discusses uterine complications after taking tamoxifen and mentions the increased risk of developing cancer of the womb.

Tamoxifen can also interact with other medications such as warfarin and types of antidepressants.
 
Some women said they felt wary of completing their hormone therapy or reluctant to stop. One woman said she had withdrawal symptoms. A few wanted to take tamoxifen in order to feel they were doing all they could. Others, however, were pleased not to be taking any more medication.

A few discussed the reasons they were not given tamoxifen or why they declined it. Doctors prescribe drugs if they believe that the additional chance of cure outweighs the side effects. The patient has a chance of weighing pros and cons and many emphasise that the benefits of treatment outweigh the temporary side effects. Some of the side effects with tamoxifen occur on placebo.

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See also 'Tamoxifen for men with breast cancer'.

Last reviewed May 2015.
Last updated May 2015.

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