A blood test that could pick out which men with advanced prostate cancer would benefit from new drug treatment olaparib has been developed.

Prostate cancer is the most common cancer in men.

The new test detects cancer DNA in the blood, helping doctors check whether precision drugs are working.

However, larger studies involving more men needed to take place to confirm if doctors could rely on the test.

Blood samples from 49 men with advanced prostate cancer were collected by researchers, as part of the phase II clinical trial of olaparib.

This type of precision drug is seen as the future of cancer medicine but because it is a targeted treatment, the drug does not work for everyone.

Researchers from The Institute of Cancer Research and the Royal Marsden NHS Foundation Trust said the test could help target treatment better and also reduce its side effects.

They used the test to identify men who were not responding to the treatment in 4 to 8 weeks and also to pick up signs that the cancer was evolving and becoming resistant to the drugs.

Prof. Johann de Bono, consultant medical oncologist at the two organizations, said: “From these findings, we were able to develop a powerful, three-in-one test that could in future be used to help doctors select treatment, check whether it is working and monitor the cancer in the longer term.”

“Not only could the test have a major impact on treatment of prostate cancer, but it could also be adapted to open up the possibility of precision medicine to patients with other types of cancer,” he added.