Tamoxifen to prevent breast cancer?

The Independent and the Daily Telegraph published articles yesterday saying that less than half of all GPs knew that Tamoxifen can reduce the risk of breast cancer, and that they are denying women this cheap drug that could slash their risk of breast cancer by 40%.

I thought I’d try and explain this a little, as it’s not as simple as – take Tamoxifen and you won’t get breast cancer. It may be that GPs need to be educated about the benefits of Tamoxifen, but we also need to educate the patients so they can make their own, well-informed choice.

Tamoxifen is routinely given to women with oestrogen-sensitive breast cancer. It blocks oestrogen in breast cells and reduces the risk of recurrence. Based on several studies showing that Tamoxifen can reduce the risk of breast cancer, NICE recommended that Tamoxifen should be offered to all high risk women (>30% chance of developing it in their lifetime), and may be offered to moderate risk women (17-30% chance not developing it in their lifetime). It is most effective in women over the age of 50, and can only be taken for 5 years, although the benefits last 10-20 years. So why don’t we offer it to everyone?

Well, Tamoxifen has a lot of side effects, similar to the menopause. Whilst some women sail through it, others suffer with hot flushes, night sweats, weight gain, mood swings, depression, vaginal dryness and loss of libido. You have to stop taking HRT. Tamoxifen causes birth defects so you have to use regular contraception. There is also a very small but very real risk of womb cancer and blood clots in the lung, which can kill. Finally, up to 30% of women with breast cancer will still get a recurrence despite taking Tamoxifen.

Tamoxifen is also only effective against breast cancers that are sensitive to oestrogen. 30% of breast cancers are not sensitive to oestrogen, and a lot of women with the BRCA genes which put them in the higher risk category will develop tumours that are not sensitive to oestrogen, and Tamoxifen cannot protect against these. The drug also isn’t licensed in the UK to prevent breast cancer, which theoretically means a patient could sue her doctor if she developed a complication.

How do you know what your risk is? If you are worried about your family history of breast cancer, this chart can help you decide whether you need to speak to your GP about it. For example, if you only have one relative with breast cancer, she/he needs to be your mother, brother or sister AND be diagnosed before the age of 40 for you to be considered as moderate risk. If your relative was your granny in her 70s, then you are not at an increased risk.

One of the simplest ways to reduce your risk of breast cancer is to stay active and maintain a healthy weight. Make sure that you are breast aware and check your breasts regularly. Breast Cancer Care tell you what to look out for.