Worldwide study links two new genetic variants to Breast Cancer

A worldwide study of the DNA of 100,000 women has discovered two new genetic variants associated with an increased risk of breast cancer. The genetic variants are specifically linked to the most common form of breast cancer, oestrogen receptor positive, and provide important insights into how the disease develops.
Scientists believe screening women for all the genetic variants so far identified could eventually pick out those at highest risk of breast cancer and improve strategies for preventing the disease.
The study was led by scientists at The Institute of Cancer Research, London, and is published today in Human Molecular Genetics. It analysed the DNA of around 86,000 women of European, 12,000 of Asian and 2,000 of African ancestries, around half of whom had breast cancer.
The study's identification of two new genetic risk factors for breast cancer provides important clues about the causes of the disease - implicating a gene called KLF4, which is thought to help control the way cells grow and divide. The research involved scientists from more than 130 institutions worldwide - also including the London School of Hygiene and Tropical Medicine, and the University of Cambridge. It was funded by a range of organisations including Cancer Research UK, Breakthrough Breast Cancer and the European Union. Researchers were looking for one-letter differences in DNA code that were more likely to be found in women with breast cancer than those without the disease, using a state-of-the-art genetic technique called 'fine mapping'. They focused on a recently identified hotspot for genetic causes of breast cancer on chromosome 9.
Women with the first genetic variant identified, called rs10816625, were 12 per cent more likely to develop breast cancer than women without, and those with the second variant, rs13294895, at a 9 per cent increased risk.
The increases in risk were slightly higher,14 per cent and 11 per cent respectively, for oestrogen receptor positive breast cancer, but there was no association with oestrogen receptor negative forms of the disease.
"Our study zoomed in on an area of our genome that we knew was linked to breast cancer risk, and has identified two new genetic variants that add significantly to our knowledge about the genetic causes of the disease."
"The variants we identified are specifically associated with the most common, oestrogen receptor positive, form of breast cancer. The more genetic risk factors for breast cancer we discover, of which there are currently more than 80, the more accurately we will be able predict who is at risk of getting the disease. Ultimately this will be vital for designing preventative strategies against breast cancer."