A study has found that more than 80% of participants carrying genes linked to breast cancer didn’t know they had them. The research paper, called ‘Exome Sequencing-Based Screening for BRCA1/2 Expected Pathogenic Variants Among Adult Biobank Participants’and published in JAMA, tested more than fifty thousand people for the BRCA1 and BRCA2 variants linked to cancer. To view the original study at JAMA’s website, click here. Alternatively, one of the authors of the study, Dr Murray, has written an article about the research at The Conversation.
About the BRCA1/2 Gene Variants
The BRCA1 and BRCA2 genes play an important role in repairing damaged DNA and suppressing tumours. Certain mutations in these genes can reduce their ability to carry out these functions, making some forms of cancer more likely. Changes to these two genes have been linked to multiple forms of cancer, and specific variants are associated with a greater risk of breast and ovarian cancers. For example, according to this study, approximately 70% of women with these variants develop breast cancer by eighty. This figure is much higher than the 12% of females in the general population that develop breast cancer in their life. However, importantly, not everyone who develops breast cancer will have a BRCA mutation, and not everyone with a BRCA mutation will develop breast cancer.
Screening can be a useful way to identify people who are put at risk by certain genetic variants – and this knowledge may help them to identify potential cancers faster, receive earlier treatment, and plan for the future. To find out how effective screening is a study sequenced the exomes of 50,726 adults between 2014 and 2016 to identify potentially harmful BRCA1 and BRCA2 variants.
Out of the people who took part in the study, 0.5% carried pathogenic BRCA1/2 variants (267 out of the 50,726). Of these, 82% (219) hadn’t previously had clinical testing, meaning that only 18% knew that they carried the genes. These findings could have implications for the role of preventative screening in healthcare; under the current system, this study suggests, many BRCA1/2 variants may go undetected. The researchers conclude that the BRCA1/2 mutations may be more prevalent than originally thought, and relying on a family history of cancer might not be an accurate way to judge the risk of BRCA1/2 variants.