Exposure to X-rays raises risk of breast cancer in young women with BRCA faults

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The international study, part-funded by Cancer Research UK, looked at almost 2,000 women with BRCA faults in the Netherlands, France and the UK between 2006 and 2009 to see if variations in their DNA increased the risk of breast cancer after exposure to low doses of radiation.

It found that women under 30 with BRCA faults who were exposed to chest X-rays and other radiation procedures (such as fluoroscopies, X-rays, mammograms and CT scans) were 43 per cent more likely to develop breast cancer, compared with women with the same faults who were not exposed. But, this increased risk did not apply to procedures carried out in women over 30.

Around two per cent of breast cancers are caused by BRCA faults, and women with these faults have a 45 to 65 per cent chance of developing the disease.

In the UK, women with BRCA faults are only screened for breast cancer after they are 30, and with a procedure called MRI that does not expose them to radiation.

Study author, Professor Douglas Easton, a Cancer Research UK scientist at the University of Cambridge, said: “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. It’s important that these women and their doctors are aware of this.”

The study was led by the University of Cambridge in the UK, in association with The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, St Mary’s Hospital and Addenbrookes Hospital.

Dr Julie Sharp, senior science information manager at Cancer Research UK, said: “This research highlights that young women with a faulty BRCA gene are potentially more sensitive to low doses of radiation and doctors need to be aware of these risks when considering procedures using X-rays. 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.”

Reference

1. Pijpe, A., Andrieu, N., et al. (2012). Exposure to diagnostic radiation and risk of breast cancer among carriers of BRCA1/2 mutations: retrospective cohort study (GENE-RAD-RISK) BMJ DOI: 10.1136/bmj.e5660

klíčová slova: X-rays, BRCA genes, breast cancer