Experts agree that breast is best for your baby - but there's new evidence that it might benefit you too, by reducing the risk of breast cancer

Does breastfeeding protect you from breast cancer?

Experts agree that breastfeeding certainly does not increase the risk of developing breast cancer, and long-term breastfeeding may even reduce it.

'A number of studies, though not all, suggest a possible link between breastfeeding and a reduction in the risk of breast cancer,' according to Jackie Graveney, Director of Communications at Breakthrough Breast Cancer, 'However, there are many factors involved in whether a woman decides to breastfeed or not. Women should know as much as possible about breastfeeding so that they can make an informed decision.'

Results of studies have varied wildly. Two reports, published in 1999 and 1997, showed that pre-menopausal women had a 50 per cent lower risk of breast cancer if they had breastfed. Other studies show no conclusive link between breastfeeding and reduced risk of breast cancer.

Does the length of time you breastfeed make any difference?

The evidence for risk reduction becomes more consistent the longer women breastfeed. But, for it to make a significant difference, research suggests that a woman needs to breastfeed for a considerable length of time.

In one study, Chinese women who had breastfed for a total of six years or more over the course of their lives were found to have a 63% decrease in breast cancer incidence, compared to women who had never breastfed.

Further evidence comes from a Yale University study of US women, published in June 2001, which found that women who breastfeed their first child for more than 13 months have a slightly reduced risk of breast cancer.

How does breastfeeding protect you from breast cancer?

There are several theories. One is that breastfeeding reduces exposure to the female hormone oestrogen, which in turn reduces the risk of breast cancer.

Breastfeeding itself causes hormonal changes and delays the onset of ovulation after pregnancy, again reducing a woman's lifetime oestrogen exposure.

Another theory is that fat-soluble carcinogens and pollutants are not stored as efficiently in lactating breasts.

There is also some evidence that breastfeeding causes physical changes in breast cells that may make them more resistant to the mutations that can lead to cancer.

Does breastfeeding influence the risk of breast cancer for the baby?

There is some evidence that there may be a slight decrease in the risk of developing breast cancer among women who were breastfed as infants. This protection may be due to the hormones and immune factors present in breast milk.

Do pregnancy and childbirth protect you from breast cancer?

Women who have their first child before the age of 30 reduce their breast cancer risk, because breast cells don't completely mature until they are exposed to hormones released during late pregnancy. Once breast cells have fully developed, they are thought to be less vulnerable to chemicals and other agents that damage DNA.

According to the Cancer Research Campaign, women who have their first child by the age of 20 have 50% less risk of contracting breast cancer than a woman who has her first child after the age of 30. But nobody is suggesting that we should encourage teenage pregnancies in order to beat breast cancer.

What other factors help protect you from breast cancer?
Diet and exercise

Lean, active women have a reduced incidence of breast cancer.

The earlier a healthy lifestyle is adopted, the more effective it will be in reducing the risk of developing breast cancer. There is increasing evidence linking breast cancer to the dietary habits of girls under 10. When overweight girls reach puberty and start producing oestrogen, it ends up being stored in the fat rather than used or discarded.

Alcohol

Drinking alcohol on a regular basis slightly increases the risk of developing breast cancer, and that risk increases with intake.

Alcohol is thought to interfere with the enzymes that break down oestrogen, so relatively heavy alcohol intake can lead to higher than normal levels of the hormone.

What if you feel a lump in your breast while you're breastfeeding?

Lumps are common in the breasts of women who are breastfeeding and are unlikely to be cancer. However, breastfeeding women should still examine their breasts for changes or abnormalities. The best time to examine the breasts is immediately after a feed.

If you have had breast cancer, can you breastfeed?

Following either a mastectomy or radiotherapy you will still be able to breastfeed from your remaining healthy breast, which produces more milk to compensate.

If you have had radiotherapy, it is unlikely that your treated breast will produce much milk, although some women have breastfed successfully from the treated breast.