A team of University of Cambridge scientists, led by Dr Douglas Easton, has discovered five new genetic factors associated with the risk of developing breast cancer.

The study, which was published in the journal Nature Genetics, is the largest of its kind to date and was funded by Cancer Research UK.  

By scanning the entire genetic makeup of approximately 4,000 British patients with a family history of breast cancer, then studying the DNA of a further 24,000 thousand women with and without the disease, the researchers were able to identify five gene locations associated with a greater likelihood of breast cancer history in close relatives and within a family.

This brings to eighteen the number of identified “spots” of common genome variations linked to a higher breast cancer risk. 

According to Dr Easton, “We know for sure that these gene variations are associated with risk. It is not the whole picture but it will contribute ultimately to genetic profiling of risk.

"It also contributes to our understanding of why the disease develops and will lead to a better understanding of the biology of the disease.” 

Women with a distinct family history of breast cancer already undergo early screening for tumours, and are also currently eligible for genetic tests if one of their close family members has or has had breast cancer.  

However, the eighteen genetic variations, including as the newly-identified five, are not currently screened for, and are considered accountable for roughly eight per cent of all breast cancer cases.  

Members of the breast cancer research community hailed the discovery as an important breakthrough. “This research takes us a step closer to developing a powerful genetic test for the disease,” said Dr Helen George, head of science information at Cancer Research UK.

She added, “Such a test could help doctors identify women who have an increased breast cancer risk so that they can make informed decisions about how to take steps to reduce their chance of developing the disease.” 

With 45,500 new cases announced every year, breast cancer is the most common variety of cancer in the UK.