A simple, non-invasive blood test may be able to tell how prostate cancer patients will respond to treatment, a new study by The Institute of Cancer Research in London suggests. The liquid biopsy, researchers believe, may also help pinpoint patients at a greater risk of a relapse and tailor treatment for those in more advanced stages of the illness. For the study, the team of researchers from ICR and The Royal Marsden NHS Foundation analysed almost ,1000 blood samples from prostate cancer patients. The results concluded that the tests can detect 'traces of cancer in the bloodstream' and could help track the progression of the disease as well as response to treatment. Men who were found with a higher level of tumour DNA in the beginning of treatment had a worse outcome. Patients were monitored with repeated blood tests and those who responded to treatment saw a fall in the cancer DNA.