Icelandic biotech company, DeCODE Genetics, last week launched a controversial genetic test to assess a woman's risk of the most common forms of breast cancer. The 1,625 dollar test, which has attracted criticism, comes at a time when new standards of best practice are being drawn up in the UK to try and control the boom of unregulated genetic tests now being marketed to the public.
95 per cent of breast cancer cases are non-hereditary or 'sporadic', meaning they result from multiple, interacting, environmental and genetic factors. Nevertheless, some common genetic variations have been identified that, although not solely responsible for causing specific cancers, are linked to a slightly increased lifetime risk of developing the disease.
The new test looks at seven such gene variants, known as SNPs, to help estimate a woman's lifetime risk of developing breast cancer relative to the general population. According to the American Cancer Society, the average lifetime risk for women of European descent is 12 percent and test scores could range from 4.0 times average lifetime risk to less than 0.4 times.Dr Kari Stefansson, chief executive of DeCODE, told the Washington Post: 'What this does for women is allow them to assess their personal risk for the common forms of breast cancer. That's what you need to do to make early diagnoses or take preventive measures'.
However, other scientists have argued that the test has little clinical value.
Professor Eric Winer, a breast cancer expert at Harvard Medical School and a spokesman for the American Society of Clinical Oncology said, 'There is at least a significant chance this test could falsely reassure some women and alarm others.'
Professor Mary-Claire King, a geneticist and breast cancer expert at the University of Washington, and others have questioned whether the markers used in the test have been properly scientifically validated. 'It's meaningless, and it could very easily introduce real confusion,' she said of the test. 'The idea of introducing into medical practice a test whose predictive value is completely unvetted biologically is frightening,' she added.
Furthermore, there is also widespread concern that, in the absence of professional medical advice and counselling, members of the public may misinterpret the test, which is available over the internet.
It remains unclear how accurate the test, which has been researched using women of European descent, would be for women of other backgrounds, although the company is taking steps to assess this, said Dr Stefansson.