HEALTH STYLE: The Breast Cancer Puzzle; Last Week It Was Revealed That Breast Cancer Is the Most Common Form of Cancer in the UK. It Has Been Suggested That Lifestyle Factors May Be Contributing to the Worrying Trend. Noreen Barr Finds out How Much Is Known in This Area and What Research Remains to Be Done

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Byline: Noreen Barr

The disclosure by experts that breast cancer is now the most common form of cancer in the UK will come as a shock to all women.

And suggestions that delaying motherhood could increase the chances of developing this disease will cause added consternation amongst career-minded types who are often opting to put off having babies until their midto late-30s. New research by the Cancer Research Campaign (CRC) and Imperial Cancer Research Fund (ICRF) shows that breast cancer rates have leapt 20 per cent in a decade.

An estimated 39,500 new cases are now diagnosed each year - compared to the previous leader, lung cancer, which sees around 38,900 new cases annually. Apart from a few isolated male cases, breast cancer affects only females.

Doctors are puzzled by the steady rise of breast cancer in modern times but it is thought that lifestyle factors may be contributing to this worrying trend.

Later motherhood and rising obesity rates have both been pinpointed as possible risk factors.

Professor Robert Souhami, director of clinical research at the ICRF, says a women's chances of developing breast cancer seem to depend upon her exposure to oestrogen before the menopause.

Those who begin menstruation early or experience the menopause late are exposed to this female hormone for longer and evidence suggests they are more likely to contract the disease.

Delayed motherhood may be an issue, he says because: 'Having your babies later in some way exposes you to a more oestrogen-dominated hormone environment than having them earlier.

'Nobody quite knows why this is, so there's more research to do about the mechanisms of that.'

However Souhami stresses there is no reason for women to panic and feel they should become pregnant immediately for the sake of their health.

'The clear thing to get over is that this component only accounts for a small increase in risk. What one doesn't want to do is make women feel, 'Oh my God, I'm dicing with death if I choose to have my children later.' Dr Lesley Walker, director of cancer information for the CRC, says choosing to remain childless may be more problematic than just having children late.

'There is some evidence that having children earlier decreases the risk of developing breast cancer but not having them at all probably has a more significant impact on your overall risk.'

Obesity in older women also seems to increase the chances of contracting breast cancer and Walker explains: 'The reason is extremely likely to be that when you are post-menopausal, the ovaries shut down and stop making oestrogen but the fatty tissues act as depots for the production of this hormone. …