Landmarks in prostate cancer diagnosis: the biomarkers

The main diagnostic biomarker in current use is prostate-specific antigen (PSA) and it is one of the recommended diagnostic tools from the European Association of Urology Guidelines on prostate cancer. One of the challenges with PSA is that men with very low levels of PSA can harbour prostate cancer, making it difficult to set a lower limit. Several modifications to PSA biomarker detection have been suggested to improve its sensitivity and selectivity including PSA density, free: total PSA, PSA velocity/doubling time and different PSA isoforms. However, there remains a need to improve accuracy of diagnosis and this has led to research in to a number of promising new biomarkers. These include genetic and blood or urine based biomarkers. The most advanced of these is prostate cancer gene 3 found in urine and developed into a commercial test in 2006. Other promising markers include circulating tumour cells (CTC) in blood, which have been correlated with survival in castration-resistant prostate cancer. A system for evaluating CTC was approved by the USA Food and Drug Administration in 2008.