Oestrogen is a hormone produced in the body by both men and women.
Even after the menopause (the change) women produce oestrogen and we know that some breast cancers rely on this for their growth. Endocrine therapies affect how the body’s hormones work and are designed to:
Reduce the size of an existing breast cancer.
Reduce the risk of the original cancer coming back.
Reduce the risk of a new cancer developing in women who have previously had breast cancer.
Reduce any cancer cells that may have escaped from the breast and may be elsewhere in the body.
These drugs have been carefully developed to have specific effects on breast cells only. They do not make you ‘manly’ or more/less feminine.
How long will I need to take endocrine therapy for?
Endocrine therapy is often recommended following surgery for breast cancer and in this case will usually be taken for a total of 5 years. You may be advised to take one type of tablet for 2-3 years followed by a different tablet for the remainder of the 5 years. Your doctor will discuss this with you when he/she prescribes your treatment.
Some people may benefit from taking a different hormone tablet for a further 2 or 3 years. This will be discussed with you before you are advised to stop taking your hormones tablets.
Some people will be treated with endocrine therapy alone and if so will take these tablets for life.
What are my tablets called?
There are two types of endocrine therapies:
What are anti-oestrogens?
Tamoxifen remains one of the most common anti-oestrogen treatments used for people who have had surgery for breast cancer. Anti-oestrogens work by blocking the action of oestrogen on breast cells.
Although anti-oestrogens can be prescribed for men and both pre and postmenopausal women, they are the only type of endocrine therapy that can be given to pre-menopausal women.
Are there any side effects?
As with any medication there are possible side effects but this does not mean that everybody will get them, or that the side effects will last forever.
The most common side effects are hot flushes, weight gain or occasional indigestion (this can be helped by taking Tamoxifen with food).
Other side effects include a slight vaginal discharge/dryness, mood/emotional changes, light-headedness, dizziness, headaches or skin rashes. These symptoms are usually mild and temporary but if they do not improve contact your GP or Breast Care Nurse who will advise you. Any blurred vision, pain or swelling of lower limbs should be reported to your GP as Tamoxifen can carry an increased risk of some people developing deep vein thrombosis. This will be discussed with you before it is prescribed.
Women who have not been through the menopause may notice a change in their menstrual cycle, with periods becoming less regular, lighter or they may even stop. Barrier methods of contraception should still be used by these women to avoid pregnancy (even in the absence of periods).
A slight increase in the risk of developing cancer of the lining of the womb has been reported for women taking Tamoxifen. Women who are still having periods or who have had a hysterectomy are not at any increased risk.
However it has been emphasised that the benefits of taking Tamoxifen far outweigh any of the risks. Women taking Tamoxifen should continue to go for their cervical smears when invited. If there are any problems between tests, such as bleeding after intercourse or between periods, then contact your GP or tell your clinic doctor at your next appointment.