Cancer link to fall in breast feeding
Sarah Boseley, health editor
Friday July 19, 2002
The Guardian
The cultural shift within the UK and other prosperous countries in modern
times, which has led to women having few children and breastfeeding their
babies for a few months at most, are the main causes of the surge in
breast cancer, according to a new study.
A group of scientists today publish a piece of work in the Lancet medical
journal which concludes that if women in the UK went back to an era when
they bore six children and breastfed each for two years, the numbers of
breast cancer cases would be halved.
The authors, Valerie Beral of Cancer Research UK and colleagues in the
collaborative group on hormonal factors in breast cancer, recognise the
impracticality of turning back the clock.
However, they say, the recognition that breastfeeding protects against
breast cancer may help in the discovery of drugs that can mimic the
effects. "In the meantime, important reductions in breast cancer incidence
could be achieved if women considered breastfeeding each child for longer
than they do now."
Professor Beral said: "Two and a half centuries ago, people knew that
breast cancer was common among nuns in Italy. It's been suspected for a
very long time that breast feeding and the number of children was
important - it was pretty well-known that not using the breasts for the
purpose for which they were designed was a major cause of breast cancer."
But in the 1970s, science became fixated with the age at which women first
had babies as an important factor in breast cancer. Now it seems that many
things are interlinked, but that the most important may be the number of
children and duration of breastfeeding. Professor Beral and colleagues say
in their paper that each birth reduces the risk of breast cancer by 7%,
while every year of breastfeeding cuts it by 4.3% more.
If women in the UK had the same family sizes and breastfeeding habits as
those in the developing world, they say, the cumulative incidence of
breast cancer here would be cut by more than half, from 6.3 to 2.7 per 100
women by the age of 70. Part of the reduction in risk is due to larger
families, but two-thirds of it is due to breastfeeding.
Nobody believes that women would want to increase the size of their
families, but breastfeeding for longer could be a feasible way of cutting
cancer risk. According to the paper, if women in developed countries
continued to have on average 2.5 children, but breastfed each one for six
months longer than now, then around 25,000 cancers would be prevented each
year, which is about 5% of the total. Increasing breastfeeding by 12
months would prevent 50,000 cancers, or 11% of the total today, they say.
In England and Wales in 2000, 71% of mothers started to breastfeed,
according to the Department of Health's Infant Feeding Survey. By six
weeks, only 42% were still breastfeeding and by six months, all but 21%
had given up.
Breastfeeding for the sort of length of time it is done in developing
countries would raise practical, social and cultural difficulties in many
developed countries. The 2000 survey showed that half of all mothers were
working by the time their babies were eight to nine months old, even
though mostly on a part-time basis.