Breast cancer is a disease that commonly affects women around the age of the natural menopause.

For reasons not well understood, treatments such as hormonal therapies and chemotherapy may cause further menopausal symptoms in women who have already gone through the menopause.

Many more women with breast cancer, who are pre-menopausal when diagnosed, will be pushed into the menopause early by the treatments given.
For some women this is the aim of treatment – removing the source of oestrogen to breast cancer cells, at least temporarily.

So for a large proportion of women who have been diagnosed with breast cancer, menopausal symptoms, either mild or severe, can affect their daily lives.

The main source of oestrogen and the levels in your body differ depending on whether you are premenopausal or postmenopausal:

Oestrogen before the menopause
Before the menopause, oestrogen comes primarily from the ovaries.

There are four ways to stop the ovaries from producing oestrogen:

• Surgical removal of the ovaries
• Radiation of the ovaries
• Hormonal agents
• Chemotherapy (this may depend on the type of chemotherapy and the age of the patient)

LH-RH analogues are a group of treatments that work in premenopausal women who still have regular periods. They ‘switch off’ the ovaries, preventing them from producing oestrogen and cause a temporary menopause..

These drugs have the same effect as surgically removing or irradiating the ovaries but their effect can be reversed when treatment is completed and the woman’s periods may start again.

Oestrogen after the menopause

• Once a woman has gone through the menopause, oestrogen is still present in the body but at lower levels.
• Only a small amount of oestrogen is produced by the ovaries. The main source is now is the adrenal glands. It is also produced by other body tissues such as fat, muscle, liver and the breast itself.
• This oestrogen can still feed hormone-sensitive tumours.

This production of oestrogen outside the ovaries is blocked by a group of drugs known as the aromatase inhibitors.

Is there a link between oestrogen and breast cancer risk?
For some people, long-term exposure to oestrogen-containing medications such as Hormone Replacement Therapy (HRT) or the Pill (oral contraceptive) will lead to a small increase in breast cancer risk.

For every 10,000 women taking HRT it has been estimated that an extra 8 will develop breast cancer. For one particular person it is very difficult to work out whether or not increased exposure to oestrogens will increase breast cancer risk.

In general, professionals think that the possible small increase in risk should not affect the decision of an otherwise healthy woman to use hormone treatments such as the contraceptive pill or HRT.

You should talk to your doctor to weigh up the small increased risk against the benefits of hormone medications.