Prostate Cancer (PCa) is a leading malignancy worldwide, especially in aging populations. In Europe an estimate of around 417.000 men were newly diagnosed with PCa in 2012 . Severity of PCa is diverse: On the one hand, many PCas are indolent with a slow disease progression. These will in most cases not become lifethreatening, even if not treated at all. Between the years 1996 and 2003, 91% of men diagnosed with PCa had stage 1 or 2 of disease and 5-year survival rates approached 100%. On the other hand, about 92.000 men died in 2012 due to PCa. In these cases, an anti-hormonal PCa therapy was not successful due to a change to androgen-independent PCa that was refractory to available therapies (castration-resistant prostate cancer (CRPC)).State of the art in screening for and monitoring of PCa is measurement of prostate specific antigen (PSA), which is widely available. An increase of PSA occurs early in the disease. PSA levels of 2-10 ng/ml do not provide information on the progress and aggressiveness of PCa in a variety of scenarios. Therefore the PSAscreening leads to a marked increase of new cases. Up to 80% of PCas are over-diagnosed, indicating that these PCas would never have caused relevant problems. Diagnosis of cancer in many cases leads to treatment of patients. Current state of the art therapies like radical prostatectomy, radiation and hormonal therapy have side effects that might surpass the benefit of treatment: even more so if the cancer is not aggressive per se. The question arises whether patients with early stage PCa benefit from radical therapy, and how to distinguish between non-aggressive, intermediate, and aggressive PCa. PSA screening has reduced PCa specific mortality, but aggressive forms of PCa are in many cases not cured by radical prostatectomy and radiation therapy. The quality of life could potentially be better without therapy and therefore fewer side effects within the remaining life-time.