Increased Chance of Breast Cancer on HRT . . . but Breastfeeding Could Give Protection against It; A Hornet's Nest of Conversy Was Stirred Up This Month by Two Major Studies about the Risk Factors Associated with Breast Cancer. So, Just What Are the Facts?
Byline: JOHN VON RADOWITZ
Two studies on breast cancer took place earlier this month concerning, firstly, the thorny issue of hormone replacement therapy and, secondly, the effects of modern western lifestyle on our health.
Both seemed to reinforce the basic principle that if you mess with nature, you end up paying for it.
The HRT study, which made front page news, involved a large clinical trial in the United States that was stopped early because of what it found.
The investigation compared the risks and benefits of long term HRT in more than 16,000 women.
It found that women who took a combination HRT pill containing oestrogen and progestogen over a period of five years had a 26 per cent increased risk of invasive breast cancer.
They were also more likely to get heart attacks, strokes and blood clots.
But it was the breast cancer risk that persuaded the doctors running the Women's Health Initiative study to halt it three years early and publish the results in the Journal of the American Medical Association.
Experts in the UK urged women not to panic, pointing out that the "absolute" risk of breast cancer from taking HRT remained very small.
For every 10,000 women on the HRT pill, just eight would develop breast cancer over the course of a year.
Nevertheless, women were advised to think carefully before embarking on a long term HRT, and the findings are certain to influence the way hormone replacement is prescribed.
The second study, by scientists at Cancer Research UK, pooled data from a host of previous research investigations around the world involving about 150,000 women.
This kind of study is called a "meta-analysis" and, because of its scale, can provide powerful evidence about patterns and trends.
Here, a strong link was found between childbirth and breastfeeding and protection against breast cancer.
The research suggested that British women could halve their risk of breast cancer if they adopted reproductive customs which existed in western Europe 100 years ago and can still be found in the third world.
Every child a woman gives birth to reduces her chances of getting breast cancer by 7 per cent, the findings showed.
On top of that, the risk is reduced by a further 4.3 per cent for each year of her life she spends breastfeeding.
Today, women in Britain have an average of two children and breastfeed for no more than about three months.
In developing countries, it's traditional for women to have several children and breastfeed each of them for as long as two years.
If UK women did the same, their risk of breast cancer would be halved, the research showed.
Even if British women breastfed for an extra six months, 1,000 cases of breast cancer would be prevented each year.
The same kind of trend has been detected by much smaller individual studies in the past.
An investigation of the medical history of 808 Chinese women by researchers at Yale University from 1997 to 1999 found that those who breastfed for two years or longer reduced their risk of breast cancer by 50 per cent. …