Chest X-rays may increase the chances of breast cancer occurring in women with a genetic predisposition to the disease, according to new study.

Scientists at the International Agency for Research in France discovered that women with defective genes linked to breast cancer (labelled BRCA1 and 2 mutations) were 54 per cent more likely to suffer from the disease if they had previously had a chest X-ray.

The study, involving 1,600 women with the defective genes, found women who were exposed to X-rays before the age of 20 more than doubled their risk of developing cancer before their 40th birthday.

Research leader Dr David Goldgar said: "If confirmed in prospective studies, young women who are members of families known to have BRCA 1 or BRCA 2 mutations may wish to consider alternatives to X-rays, such as MRI [magnetic reasoning imaging]."

Breakthrough Breast Cancer urged women not to be put off attending breast screening appointments as the study was related to the type of X-rays used to examine the heart, lungs and ribs but not mammograms which concentrate solely on the breast area.

"Mammography can detect breast cancer early, when it is more likely to be successfully treated," said Sarah Rawlings from the charity.

Since singer Kylie Minogue was diagnosed with breast cancer last year, the number of women having mammograms has risen by more than 40 per cent.