Doctors have begun a trial of a simple saliva test that aims to spot the top 10% of men who are most at risk of developing prostate cancer. One in eight men develop prostrate cancer at some point in their lives.
The test draws on more than 150 DNA markers to identify the 10% of men who have nearly a threefold greater risk of the disease than the general population, and the 1% of men with a sixfold greater risk.
Researchers created the test after a major study into the genetics of prostate cancer found 63 new gene variants linked to the disease. The new test combines these with more than 100 DNA markers that were already known from previous work.
Off the back of the findings, scientists at the Institute of Cancer Research (ICR) in London have launched a trial of the test across a small number of GPs’ surgeries with the ultimate aim of reducing cases of the cancer in men with the greatest inherited risk.
“The reason we are particularly excited by the test is that this can be offered in general practice as a spit test to really try and identify who is most at risk of prostate cancer so we can offer them targeted screening,” said Rosalind Eeles, a geneticist on the study at the ICR. Men with a high genetic risk can be screened with MRI scans and biopsies.
Prostate cancer is one of the most common forms of cancer among men in the developed world, but researchers have yet to identify actions men can take to reduce their risk. Beyond a family history of the disease, the greatest risk factors are age and ethnic background, with older men, and those with African-Caribbean or African descent, being most likely to develop the disease.
In Britain, 47,000 men are diagnosed and 11,000 die from the disease each year. The cancer is highly heritable and so runs in families: men are more than twice as likely to get prostate cancer if their father or brother has been diagnosed.
To find new gene variants linked to the disease, the ICR scientists compared the DNA of 80,000 prostate cancer patients and 61,000 healthy controls. Many of the new variants affect how the immune system talks to other cells in the body, suggesting that glitches in the body’s defences may be a driver of the disease. Other gene variants were involved in repairing damaged DNA.
The results, reported in the journal Nature Genetics, account for only 28% of a man’s familial risk of prostate cancer. The remainder is likely to come from incredibly rare mutations, or from scores of gene variants with a minuscule impact on the disease. But even with so much unknown, scientists at the ICR are keen to trial their new test to see if it can spot men who are most susceptible to the disease.
There is a desperate need for tests that can detect prostate cancer reliably and early. A March analysis of the standard PSA test found that while the screening picked up more cases of prostate cancer than would otherwise be found, it had no significant effect on survival rates.
“This new research could help men to understand their individual genetic risk of prostate cancer, which could prompt them to speak to their GP about the disease,” said Iain Frame, director of research at Prostate Cancer UK. “We urgently need more accurate diagnostic tests which are suitable for use in a nationwide screening programme and Prostate Cancer UK is investing heavily in research in this area.
“With Father’s Day fast approaching, use it as an opportunity to ask your dad, your brother, your uncle, your friends about their risk of prostate cancer. It’s a conversation that could save their life.”