Breast cancer does run in the family, major study finds

Women are nearly twice as likely to contract breast cancer if they have a mother, sister or daughter who has fallen victim to the disease, according to a landmark new study published.

Women are nearly twice as likely to contract breast cancer if they have a mother, sister or daughter who has fallen victim to the disease, according to a landmark new study published.

If women have two affected relatives, they are three times more likely to develop the disease than other women, and the risk quadruples if three first-degree relatives are affected.

But most women with a family history of breast cancer will never develop the disease and most of those who do will be over 50 when the cancer is diagnosed. The research, published in today's issue of The Lancet, also shows that 87 per cent of women who develop the disease have no family history of it.

Until now, no study has been large enough to give an accurate analysis of how likely women of different ages are to contract breast cancer, or to quantify the influence of their family history. But an international team of scientists, led by Professor Valerie Beral of Oxford University, collated the results of 52 surveys involving 160,000 women to provide detailed risk estimates.

Among women who have no family history of breast cancer, 8 per cent are likely to be diagnosed with the disease at some time during their life.

One woman in eight, or 13 per cent, with one affected close relative is likely to contract the disease by the age of 80. This rises to 21 per cent of women who have two affected relatives.

But Professor Beral, head of epidemiology at the Imperial Cancer Research Fund, said 80 per cent of women who had two affected relatives would not develop the disease themselves.

"Contrary to popular belief, the majority of breast cancers in women with a family history of the disease occur after the age of 50 rather than at younger ages," she said. "It is therefore important that women with a family history remain vigilant throughout their lives and attend screening when they are invited to."

The results, which will be used to counsel women at breast cancer clinics, suggest that survival rates are reasonably good. One woman in 13 with two affected relatives will die of breast cancer before the age of 80.