100 BRCA gene variants linked to cancer found

A large international study has identified the cancer risk associated with hundreds of mutations in the BRCA1 and BRCA2 genes. The findings will help improve accuracy when interpreting genetic test results. 

The study, led by the QIMR Berghofer Medical Research Institute in Queensland, Australia, assessed 1395 BRCA1 and BRCA2 gene mutations from patient data submitted by 114 institutions. The team determined the cancer risk associated with each variant by analysing patient health records alongside their genetic information.

The team was able to determine 94 BRCA variants that increase someone's likelihood of developing breast, ovarian, prostate and pancreatic cancers. The team was also able to identify 447 variants that could be classified as benign, or likely benign, which would not be of clinical concern if found in a patient. 

More than 20,000 BRCA1 and BRCA2 mutations have been identified in the past. The variants assessed in the study were all previously known, but the impact of each variant on the likelihood of cancer development was not known. However, as only a small subset of all identified mutations were analysed in this study, the significance of many other mutations is still yet to be determined. 

Lead author and head of QIMR Berghofer's Molecular Cancer Epidemiology Group, Dr Amanda Spurdle said: 'If we can narrow down which variants pose a danger, we can reduce concern for clinicians and patients, and avoid unnecessary testing that unfortunately sometimes occurs for individuals with a variant of uncertain significance.' 

The findings could help doctors give advice on how frequently a patient should be screened for breast cancers and whether or not they should consider taking preventative measures. 

Dr Paul James, from the Royal Melbourne Hospital's Familial Cancer Centre and also an author of the study, told ABC News: 'If a variant is not an abnormality, you do not want to be offering aggressive interventions like preventative surgery.'

The research was published in the journal Human Mutation.