The huge international collaboration analyzed the DNA of around 100,000 women with and without breast cancer.
The newly uncovered genetic variants provide clues about how this breast cancer develops, and also represent factors that could be used to screen for the women who are at the highest risk.
Led by British researchers at the Institute of Cancer Research in London, massive pooling of scientific data was needed to identify the "single nucleotide polymorphisms" - small variations in the genetic code - that signalled breast cancer susceptibility among the DNA of around 100,000 women.
Some 130 teams of researchers from around the world worked together to standardize their methods of genetic analysis to deliver powerful results.
Presented in the journal Human Molecular Genetics, the analysis used the DNA of around 86,000 women of European ancestry, 12,000 of Asian, and 2,000 of African ancestry. About half of the women under analysis had breast cancer.
The researchers believe that the two variants - labeled rs10816625 and rs13294895 - influence a gene known as KLF4, thought to be involved in the control of cellular growth and division.
The study found that the increased risks of cancer presented by each of these polymorphisms were:
- For women carrying rs10816625, versus those without it, a 12% greater chance of developing breast cancer
- For rs13294895, a 9% greater risk.
Dr. Nick Orr, who heads the complex trait genetics team at The Institute of Cancer Research (ICR) in London, UK, led the study. He explains: "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."
Dr. Orr adds:
"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 preventive strategies against breast cancer."
Dr. Matthew Lam, senior research officer at the British cancer research non-profit Breakthrough Breast Cancer, says medicine is as yet unable to make accurate forecasts in breast cancer.
"Whilst we are learning more and more each day about the environmental, genetic and lifestyle factors that affect breast cancer risk," Dr. Lam says, "it is not yet possible to predict who will get breast cancer, and for women who have been diagnosed with the disease, we can't yet say what caused it."
Worldwide effort creates detailed picture of breast cancer
Professor Paul Workman, ICR's chief executive, gives a nod to the massive research effort: "Studies like this are only possible through international collaboration between huge numbers of researchers at institutions across the world, collating together data on enormous numbers of people."
The present study is the most recent in a long list to have come out of the collaborators' investigations into breast cancer genetics.
Coordination of the multinational work shared by genetic researchers is partly funded by the non-profit Cancer Research UK with support from the European Union.
Known as the Breast Cancer Association Consortium or BCAC, it is coordinated from the genetic epidemiology unit at the UK's University of Cambridge.
Dr. Emma Smith is a senior science information officer at Cancer Research UK. She adds to the idea that the collaborative research is enhancing the ever-growing genetic knowledge:
"Thanks to modern technology we're building an increasingly detailed picture of the small variations in DNA that can influence a woman's risk of breast cancer."
Dr. Smith says:
"The next challenges are understanding the biology underpinning their effects, so we can use this information to predict individual risk more accurately, improve screening and find better ways to treat and prevent breast cancer."
In just the past month, two separate genetic discoveries have added to the canon of publications in breast cancer research, both concerned with an aggressive form of the disease, known as triple negative, that appears in around 10-20% of cases. Learn more via these headlines: