Thus, a search for new biomarkers which could be more specific for the detection of prostate
cancer is needed. The use of biomarkers such as percent free PSA (Lee, 2006), intact serum
PSA (Steuber, 2002), serum pro-PSA(Lein, 2005) and kallikrein (Stephan, 2000) have shown
to be useful in the detection of prostate cancer. However, although a biomarker could
improve the precision of screening it is possible that in clinical practice it is not viable, for
the need of fresh samples or high costs (Villanueva, 2006).
The use of PSA velocity has been suggested, an increase of more than 0.