Prostate cancer (CaP) is the most common cancer in men in the UK and its incidence is increasing. The natural history of the disease is very variable, in some men progressing rapidly while in others It will run a more indolent course, in early disease localised to the prostate, radical treatment options offer potential cure however these come with considerable potential morbidity and a significant proportion of patients will relapse despite such interventions. This suggests the presence of microscopic disease beyond the prostate, not clinically detectable using current staging modalities.