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A new test that detects aggressive prostate cancer from a blood sample could save thousands of lives.

The test identifies prostate cancer patients with aggressive forms of the disease, whose risk of dying is 10 times higher than men with slow-growing, relatively harmless tumours, allowing doctors to personalise the treatments given to individuals at an early stage, say scientists at Queen Mary University of London.

A patient's blood sample is examined using a highly sensitive technique that detects tiny amounts of cells that are shed by a tumour as it grows, allowing doctors to calculate the risk of the disease spreading through the body.

An initial trial, published in the Clinical Cancer Research medical journal, found that the method identifies patients whose cancers will metastasise (spread) with 92% accuracy. Existing techniques are thought to be 80% accurate.

Among men diagnosed late with aggressive prostate cancer, only 22% survive for 10 years – compared with 99% who are diagnosed very early. The new test uses cell-capture technology to collect tumour fragments that have broken away from the primary cancer.

US professor Bert Vogelstein told the American Society for Clinical Oncology conference in Chicago this month that the tests could eventually prevent 45% of cancer deaths by diagnosing tumours before patients develop symptoms.