Researchers have discovered that genetic screening can be used to determine breast cancer risk, improving disease prevention by directing attention where it is needed.

In a study published in the Journal of the National Cancer Institute, researchers led by the Institute of Cancer Research, London showed that testing differences in the 77 separate letters of the DNA code could identify how much at risk a woman is for developing breast cancer. Over 65,000 women were involved in the study, which was supported by a number of organizations, including Breakthrough Breast Cancer and Cancer Research UK.

During the study, researchers produced a scoring system based on the letters each subject had in the 77 positions in the DNA code with the help from the Collaborative Oncological Gene-Environment Study, the most comprehensive database for genetic information in the world.

A link was found between the women's scores and their level of breast cancer risk. Say a woman has a score that puts her in the top 20 percent of the system; this puts her 1.8 times likelier to develop breast cancer compared to the average woman. A woman belonging to the top 1 percent will have over three times more risks of developing the disease than average.

The researcher also explored other elements in a woman's cancer, like type and at what age the disease was diagnosed. The study's scoring system was particularly accurate in predicting cancer risk in those that were diagnosed with an estrogen receptor positive type of cancer, the type that responds the most to hormonal treatments.

The study allowed for a wider range of genetic markers to be analyzed so the researchers were able to more accurately define risks. It also suggested that taking advantage of genetic screening alongside other tests currently in place can offer better risk assessments for breast cancer.

"Our study is the most definitive so far to show the clear benefits of using genetic testing for a large number of genetic risk factors in identifying women at elevated risk of developing breast cancer," said Montserrat Garcia-Closas, an epidemiology professor from the Institute of Cancer Research, London and co-leader for the study.

Douglas Easton from the University of Cambridge, the study's co-lead, said there's still more to be done to further discover how genetic screening can complement other factors to determine cancer risk but major steps have been taken toward the right direction.

Photo: Duncan Hull | Flickr