LONDON (Reuters) - British scientists confirmed on Friday what researchers have long suspected--breast-feeding reduces a woman's risk of developing breast cancer.

Along with having several children, breast-feeding is a key factor in the discrepancy between low rates of breast cancer in developing countries and the rising number of cases in wealthier nations.

"The longer women breast-feed, the greater protection against breast cancer," Professor Valerie Beral, of the charity Cancer Research UK, told a news conference.

Beral and her team estimate that if women breast-feed each of their children for an additional 6 months they could cut their life-time risk of developing breast cancer from 6.3% to 6% and prevent more than 1,000 cases of the disease each year in Britain alone.

"What we have shown is that prolonging breast-feeding and having more children pushes down breast cancer rates," Beral added.

Breast cancer is the most common cancer in women. A family history of the disease, early puberty, late menopause and not having children are factors that increase the chance of a woman developing the disease.

Scientists first suspected that having children and breast-feeding could have a protective effect against the disease as far back as 1743 when a study showed that nuns had high rates of breast cancer compared to other women.

Other research has linked the number of children and the age of the woman when she first gives birth with the disease but the latest study, which is published in the July 20th issue of The Lancet medical journal, is the most comprehensive in examining the role of breast-feeding.

Beral and her colleagues analyzed data from 47 studies done in 30 countries of 50,000 women with breast cancer and 100,000 healthy volunteers.

They calculated that for every year a woman breast-feeds, it cuts her risk of breast cancer by 4.3%. Their findings help to explain why breast cancer rates are so low in developing countries where women may have six or seven children--compared to two or three in western countries--and they breast-feed each child for up to 2 years.

Women in developed countries feed their children naturally for about 2 or 3 months. Fifty percent of mothers in the United States, about 25% in Europe and about 10% in Scandinavia choose not to breast-feed.

Beral calculated that if western reproductive and breast-feeding habits mimicked those in poor countries, a woman's breast cancer risk by the age of 70 would fall from 6.3 per 100 women to about 2.7.

The National Childbirth Trust, which promotes breast-feeding, said the research clearly shows the benefits for mothers as well as children.

"We hope that this important finding--that the longer women breast-feed, the more they are protected from breast cancer--will encourage more women to consider breast-feeding their baby," said Belinda Phipps, the chief executive of the trust.

The scientists are not sure how childbirth and breast-feeding reduce breast cancer risk but they believe the findings could pave the way for better prevention and treatment methods.

"It is likely to do with hormones and reproductive behavior," said Sir Paul Nurse, the Nobel Prize winning interim chief executive of Cancer Research UK.

SOURCE: The Lancet 2002;360:187-195.

Reference Source 89

For more information on how to prevent other diseases, use
PreventDisease.com's "Quick Prevention Resources".