According to new research X-rays may significantly increase the risk of breast cancer in women who are genetically susceptible to the disease.

In a study of 1,600 women with high risk BRCA1 and 2 gene mutations, recognised as increasing the risk of both ovarian and breast cancer it was found that having a chest X-ray could double or even triple the risk.

According to lead researcher Dr. David Goldgar of the University of Utah School of Medicine, it is unclear at present which kind of chest X-rays pose the greatest risk.

Mammograms were specifically excluded from the study.

Dr. Goldgar said BRCA proteins played a key role in repairing damage in breast cells and women carrying mutated versions of the genes may be less able to repair any damage associated after exposure to the ionizing radiation emitted by X-rays.

The team asked the women whether they had ever had a chest X-ray, if it was before age 20, and how many they had been exposed to.

Dr. Goldgar says the study is one of the first to demonstrate that women genetically predisposed to breast cancer may be more susceptible to low-dose ionizing radiation than other women.

He says young women from families known to have BRCA1 or BRCA2 mutations were 54% more likely to develop breast cancer than women who had never undergone the procedure and should consider alternatives to X-ray, such as MRI.

The team is now trying to gather more precise details from the women on what kinds of X-rays they had and when.

Experts in breast cancer say in general that the study though interesting is inconclusive but any information on factors which may alter their risk in this group of women is useful.

It is important they say for women to attend their breast screening appointments as mammography can detect breast cancer early when it is more likely to be successfully treated.

The Journal of Clinical Oncology study was led by the International Agency for Research on Cancer in France.