Mammograms may increase risk of breast cancer in some women

Women carrying mutations in their BRCA genes may be more susceptible to breast cancer if exposed to diagnostic chest X-rays before the age of 30, say scientists.

'BRCA genes help repair DNA damage — damage which can be caused by exposure to radiation like X-rays. Women with faults in these genes are less able to repair damage caused by radiation, so they are at a greater risk of developing breast cancer', said Professor Douglas Easton, a UK Cancer Research scientist and one of the authors of the study at the University of Cambridge.

Approximately one in 400 women carry mutations in their BRCA genes. The study, published in the British Medical Journal, enrolled almost 2,000 women with faulty BRCA genes from the UK, France and the Netherlands. Of these women, those who were exposed to chest radiation before the age of 30 were found to be 43 percent more likely to develop breast cancer, when compared to those women with BRCA mutations who were not.

The results of the study estimated that for every 100 women with faulty BRCA genes, nine would develop breast cancer by the time they reached the age of 40. Researchers then projected that if 100 women with faulty BRCA genes were exposed to radiation from one mammogram before the age of 30, the number who would go on to develop breast cancer would increase to 14.

Dr Anouk Pijpe, one of the authors of the study from the Netherlands Cancer Institute, said: 'We believe countries who use mammograms in women under 30 should reconsider their guidelines. It may be possible to reduce the risk of breast cancer in (high-risk) women by using MRIs [magnetic resonance imaging], so we believe physicians and patients should consider that'. MRIs, unlike traditional mammograms, do not use radiation to scan the breast tissue.

Dr Julie Sharp, senior science information manager at Cancer Research UK, said: 'In the UK younger women are already screened using MRI scans rather than mammograms to avoid these risks — but this isn't the case in all countries yet'.