The study, published today in Nature Genetics, was led by teams at the University of Cambridge and Université Laval, Quebec.
Current genetic tests for breast cancer only consider a few genes, such as BRCA1, BRCA2, and PALB2. However, these only explain a minority of the genetic risk, suggesting that more genes remain to be identified.
Researchers looked at genetic changes in all genes in 26,000 women with breast cancer and 217,000 women without breast cancer. These included women from eight countries in Europe and Asia.
Professor Douglas Easton, Director of the Centre for Cancer Genetic Epidemiology at the University of Cambridge, who co-led the study, said: "To our knowledge, this is the largest study of its kind. It was made possible through the use of data from multiple collaborators in many countries, as well as publicly available data from the UK Biobank.”
The team found evidence for at least four new breast cancer risk genes, with suggestive evidence for many others. The team say identification of these new genes will contribute to our understanding of the genetic risk of breast cancer and help improve risk prediction by better identifying those women at higher risk of the disease.
The findings will better inform approaches to breast screening, risk reduction and clinical management. The aim is to integrate this information into a comprehensive risk prediction tool currently used worldwide by health professionals.
"Improving genetic counselling for high-risk women will promote shared decision-making regarding risk reduction strategies, screening and determination of treatment options," said Professor Jacques Simard of Université Laval, co-lead of the study.
“Although most of the variants identified in these new genes are rare, the risks can be significant for women who carry them. For example, alterations in one of the new genes, MAP3K1, appear to give rise to a particularly high risk of breast cancer.”
Before this information can be used in a clinical setting, scientists need to validate the results in further datasets.
"We need additional data to determine more precisely the risks of cancer associated with variants in these genes, to study the characteristics of the tumours, and to understand how these genetic effects combine with other lifestyle factors affecting breast cancer risks," added Professor Easton.
The discovery of these novel genes also provides crucial information on the biological mechanisms underlying cancer development, potentially opening the way to identifying new treatments.
The study was funded by the Government of Canada through Genome Canada and the Canadian Institutes of Health Research, the Ministère de l’Économie et de l'Innovation du Québec through Genome Québec, the Quebec Breast Cancer Foundation, the European Union Horizon programme, the Wellcome Trust and the International Alliance for Cancer Early Detection.
Wilcox, N et al. Exome sequencing identifies breast cancer susceptibility genes and defines the contribution of coding variants to breast cancer risk. Nat Gen; 17 Aug 2023; DOI :10.1038/s41588-023-01466-z
Adapted from a press release by Université Laval