Prostate cancer is the most common cancer to affect men in the UK - more than 30,000 are diagnosed with it each year. Researchers are working hard to find a better blood test than prostate-specific antigen (PSA). The problem with this test is that although the PSA level is raised in up to 80 percent of men with prostate cancer, two-thirds of those with a raised level do not have prostate cancer.

Cancer patients produce antibodies that fight against antigen proteins in cancer tissue. Researchers at the University of Michigan reported in the New England Journal of Medicine (22 September) an investigation of these antibodies to see if they can be used as a diagnostic test. They scanned 2,300 antigens from prostate cancer tissue and found 186 that reacted with blood from the men with prostate cancer. 59 patients with prostate cancer and 70 normal controls were tested and 22 antigens were selected that best distinguished those with prostate cancer  from controls.

They then tested this panel of 22 antigens against an independent set of 60 serum samples from patients with prostate cancer and 68 from controls. It was found that 88 percent of samples from controls were correctly identified and 82 percent of samples from cancer patients gave a positive result. These results were significantly better than those for PSA, although there were still some incorrect results.

Further work will be needed to simplify the test and to examine larger numbers of men to determine its cost-effectiveness before it can be applied more widely.