Saliva test at GP surgery will show risk of cancer

A SIMPLE test for the genetic risk of cancer could be routinely ­carried out by family doctors within five years.

The development follows a mass study to identify a range of genetic markers linked to breast, prostate and ovarian cancers.

And a straightforward ­saliva test could, in future, reveal whether a patient is at risk.

They could then be monitored closely for the first signs of developing cancer, or – in highrisk cases – be offered preventative treatment. Experts believe the cheap and easy tests could be conducted in GPs’ surgeries.

Samples would initially be sent off to laboratory specialists, but eventually GPs could be doing the analysis themselves.

“We’re on the verge of being able to use our knowledge of these genetic variations to develop tests that could complement breast cancer screening and take us a step closer to having an effective prostate cancer screening programme,” said study author Professor Doug Easton, a Cancer Research UK scientist from ­Cambridge University.

Ovarian cancer tests are also envisaged, but will take longer to develop after more research.

The international scientists compared the DNA of more than 100,000 cancer patients with a similarly sized sample from the general population.They used microchip technology capable of identifying more than 200,000 genetic variants, some of which were suspected of being linked to cancer.

The analysis highlighted more than 80 inherited regions of the genetic code that increase an individual’s risk of developing one of the three cancers.

Each variant – a one-letter change in the code called a single nucleotide polymorphism (SNP) – has a small impact on cancer risk on its own. But added together, large numbers of the variants greatly increase the chances of disease.

In the case of prostate cancer, men in the top 1 per cent of the risk table are 4.7 times more likely than average to develop the disease.

Half of all men in this category who also have a strong family history of prostate cancer can expect to succumb to the illness during their lifetime.

Similarly, just under a third of women in the 1 per cent of those most at risk of breast cancer are likely to develop the disease. This excludes women carrying the well-known high-risk genes BRCA1 and BRCA2.

For ovarian cancer, being in the top 1 per cent for having many of the variants more than doubled the lifetime risk from 1.8 per cent to 4 per cent.

A total of 23 new genetic risk factors for prostate cancer were found, raising the known total to 78.

Of these, 16 were associated with aggressive and life-threatening forms of the disease.

The number of SNPs linked to breast cancer was more than doubled to 49, while 11 new variants that raise the risk of ovarian cancer were found.

More than 1,000 scientists from 130 institutions in Europe and the US took part in the Collaborative Oncological Gene-environment Study (Cogs).

Professor Ros Eeles, of the Institute of Cancer Research in London, said: “Eventually, testing will be at the point of care and the person making the decision is very likely to be your GP.”