Hormones produced in pregnancy can help young women stave off breast cancer in later life, scientists claimed yesterday.

About ten per cent of western women will develop breast cancer at some stage but a new study confirms previous findings that a full-term pregnancy when a woman is still young significantly reduces the risk.

In experiments on rats, US scientists found that pregnancy hormones influence the activity of a gene called p53, which produces a protein that helps to suppress tumours.

The gene blocks the amount of cancer-producing cells in the lining of the mammary glands after exposure to a trigger such as oestrogen which, it is believed, can also cause breast cancer.

Production of oestrogen is reduced during pregnancy, leaving women who fall pregnant earlier at a much reduced risk.

Scientists at Baylor University in Texas, led by Bert O'Malley, published their findings in the journal Proceedings of the US National Academy of Sciences.

Meanwhile, US scientists who helped map human DNA are about to lead the world's largest research project into the genetic causes of cancer.

The £36 million study, to be carried out at the Wellcome Trust Sanger Institute in Cambridgeshire, will be headed by professor Mike Stratton.

He and his team will search for genetic mutations which cause the most common forms of cancer which affects the breasts, lungs, rectal organs, ovary and prostrate.

'There are more than 100 types of cancer but we need to understand what makes them all different,' Prof Stratton said last night.

The data will be used to develop more powerful anti-cancer drugs.

Source: Metro, Tuesday, October 16, 2001