The oral contraceptive pill may increase the risk of breast cancer being passed down the generations, researchers have found.

The oral contraceptive pill may increase the risk of breast cancer being passed down the generations, researchers have found.

An American study of 426 families in which at least one member had been diagnosed with breast cancer has shown that the daughters and sisters of the women affected were three times as likely to develop the disease if they had taken the Pill than daughters and sisters who had not taken it.

The finding was described as "bad news" for women with a family history of breast cancer by an American specialist, but was dismissed by the leading British cancer epidemiologist, Valerie Beral, as "a tiny ripple in the evidence" showing that the Pill is safe.

Professor Beral, of the Imperial Cancer Research Fund's unit at the Radcliffe Infirmary, Oxford, led the world's largest and longest study of oral contraceptive use, published last year, which followed 46,000 women over 25 years and gave the Pill a clean bill of health. It included 2,000 women with breast cancer who had a family history of the disease and had used oral contraceptives, compared with 153 women in the new American study.

Professor Beral said yesterday: "We looked at family history and whether the Pill had an effect [on breast-cancer risk in close relatives] and found it was exactly the same as for everyone else. Having a family history of breast cancer increases the risk by one and a half to two times [in close relatives] and current Pill use multiplies that by 20 per cent. It's a 20 per cent increase not a three-fold increase and that is known and based on firm evidence."

About three million women currently use the Pill in Britain and 300 million have used it worldwide. Introduced to the United Kingdom in 1961, it ushered in an era of sexual freedom for women but there have always been fears about side-effects.

The American study, by Dawn Grabrick and colleagues at the Mayo Clinic, Rochester, Minnesota, is based on the families of patients diagnosed with breast cancer between 1944 and 1952. It included 394 sisters and daughters of the original breast-cancer patients, interviewed between 1991 and 1996, 3,002 granddaughters and nieces, and 2,754 women who married into the families. Breast cancer occurred in 153 of the blood relatives and 86 of those who married in during the follow-up period after 1952. Half the women had used oral contraceptives at some time.

The risk of breast cancer was 3.3 times higher in sisters and daughters who had ever used oral contraceptives compared with those who had not.

The authors of the study, published in the Journal of the American Medical Association, warn that the results relate to women who took the Pill before 1975, when it contained higher levels of oestrogen, and it was uncertain what effect the modern low-dose brands would have. But in an accompanying commentary, Dr Wylie Burke of the University of Washington, Seattle, says the finding is "bad news" for women with a family history of breast cancer, especially those at very high risk.

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