A new blood test could predict which men with advanced prostate cancer will respond to new targeted treatments for the disease.

Researchers were able to detect tumour DNA in men's blood and pick out cancers with multiple copies of the androgen receptor gene, which many prostate cancers rely on to grow.

Men with multiple copies of the gene responded much less well than otherwise to the targeted therapies abiraterone and enzalutamide - now standard treatment for advanced prostate cancer.

The test will have to be assessed further in clinical trials, but the researchers say it costs less than £50 and could be used in clinical practice to personalise treatment.

A team at The Institute of Cancer Research, London, and The Royal Marsden NHS Foundation Trust, along with colleagues in Europe, analysed blood samples from 265 men with advanced prostate cancer who were being treated with abiraterone or enzalutamide, either before or after docetaxel chemotherapy.

Abiraterone and enzalutamide are excellent treatments for advanced prostate cancer and some men can take these drugs for years without seeing a return of their cancer. But in other men, these drugs do not work well and the disease rapidly returns.

Researchers have developed a robust test that can be used in the clinic to pick out which men with advanced prostate cancer are likely to respond to abiraterone and enzalutamide, and which men might need alternative treatments.