A large international study confirms that women who inherit a particular gene alteration have an increased risk of developing breast cancer. The CHEK2 gene mutation appears to double a woman's lifetime risk of the illness, from around 12 to 25 per cent. The researchers, who published their findings in the journal Nature Genetics, say that it is not yet clear if CHEK2 genetic testing would be clinically useful.
Scientists at the Institute of Cancer Research in London first reported the link between CHEK2 and familial breast cancer two years ago. Now, an international consortium has studied over 20,000 women, to see how often the altered gene is present in breast cancer patients with no family history of the disease. The scientists looked at 10,860 women with breast cancer and 9,065 unaffected women living in the UK, Australia, Finland, Germany and the Netherlands.
They found the CHEK2 mutation in 201 of the affected women (1.9 per cent), and in 64 healthy individuals (0.7 per cent). The results indicate that inheriting the altered gene increases a woman's lifetime risk of breast cancer from around one in nine to one in four. However, CHEK2 mutations are 'low risk', compared to mutations in the BRCA2 and BRCA1 genes, which can increase a woman's lifetime risk to 85 per cent.
Women with a strong family history of breast or ovarian cancer are already offered BRCA1 and BRCA2 genetic testing. According to Doug Easton, leader of the latest study, the next step will be to find out whether testing for CHEK2 would be useful in the clinic. 'At the moment it is not clear in what context CHEK2 testing would be appropriate', he said. Professor Robert Souhami, of Cancer Research UK, said: 'Identifying the first of a new set of breast cancer genes puts us in a much better position to tackle breast cancer, both through testing high-risk groups and eventually through new clinical strategies'.