Tamoxifen (also known as Nolvadex, Tamofen and Genox) is a drug widely used to treat breast cancer.

Tamoxifen blocks the effect of oestrogen, a female hormone, in the breast. The growth of some breast cancers is thought to be stimulated by oestrogen.

When is it used?

Many (but not all) women are advised to take Tamoxifen after surgery and radiotherapy to reduce the risk of breast cancer returning. It is most often used in women who have passed menopause. Often it is not advised for women at low risk of breast cancer returning.

Sometimes women who are very old are advised to take Tamoxifen instead of having surgery.

Tamoxifen may also be used to treat breast cancer if it returns.

Dosage

Tamoxifen is taken as a tablet, usually one tablet (20 mg) each day. Sometimes two tablets (40mg) daily are recommended. To help prevent the return of breast cancer, Tamoxifen is usually taken for 2-5 years. Taken it beyond this time has been shown to be of no benefit and may increase side-effects.

If breast cancer has returned, Tamoxifen is usually taken for as long as it helps.

Side effects

Many women on Tamoxifen experience side-effects. Side-effects are usually mild and can include:

• hot flushes
• periods stopping
• bleeding or discharge from the vagina
• dry or itchy vagina
• nausea
• dizziness
• skin rash
• headache
• weight gain.

Some of these effects may disappear in 1-2 weeks. If they are a problem, talk to your doctor.

If you are taking other medicines, especially Warfarin or coumarin-type anti-coagulant drugs , tell your doctor.

When to take Tamoxifen

If you have nausea, try taking Tamoxifen with food or just before bed. If you miss a tablet, take it as soon as you remember. Then continue to take your tablets as before.

It's best to consult your doctor before stopping Tamoxifen. If you stop, you may get spotting.

Benefits

When used after surgery for breast cancer, Tamoxifen delays or prevents the return of cancer in 10-20% of women. It also helps to reduce the chances of cancer occurring in the other breast.

When used after breast cancer returns, Tamoxifen helps control the cancer in 20-50% of women.

Some studies suggest that Tamoxifen may reduce the risk of heart disease and bone loss in women who are past the menopause.

Risks

Taking Tamoxifen increases your risk of cancer of the uterus (womb). You have a low risk of this cancer before menopause. After menopause, taking Tamoxifen increases your risk from about two in 1000 to four in 1000 over five years.

For women at risk of having their breast cancer return, the benefit of taking Tamoxifen clearly outweighs the risk of developing cancer of the uterus. If detected early, cancer of the uterus almost always can be successfully treated, usually by hysterectomy.

If you are taking Tamoxifen and have any of these symptoms, you should see your doctor:

• abnormal vaginal bleeding including bleeding after menopause (if you have a uterus), bleeding between periods and heavier than normal periods
• changes in discharge from the vagina
• abdominal pain or pressure.

Very occasionally Tamoxifen causes eye damage, for example, damage to your cornea or retina. Ask you doctor to refer you to an ophthalmologist (eye specialist) if you have any of these symptoms:

• blurred vision
• change in colour vision.

Tamoxifen may cause harm to an unborn child if taken during pregnancy. If you could become pregnant, you should use a cap or condom with a spermicide, or an IUCD, but not the contraceptive pill. If you become pregnant, you should stop taking Tamoxifen and inform your doctor.

If you have any questions or concerns about Tamoxifen, consult your doctor