Defining ITH in prostate cancer will provide important insights into the genetics of prostate cancer development and metastatic progression and is a key prerequisite for the development of reliable personalized cancer medicine approaches. Thus this study will significantly advance researchers' efforts to predict which tumours are dangerous and in need of urgent treatment and those that could safely be left untreated which would spare these patients the unnecessary side effects. Investigators think that this research work will have a major impact on the use of next generation sequencing in the management of prostate cancer through an in-depth understanding of how common are differences between and within individual cancer lesions. Investigators also want to find out whether these differences, if they exist, are important in tumour development and spread to other areas. Investigators think that the characterization of these differences will allow them to successfully use this information to group patients undergoing treatment using molecular 'signatures' so that treatment is targeted rather than applied in a 'sledge-hammer' approach. Investigators believe that without studies like PROGENY, doctors will instead rely on data from single tumour biopsies which can be misleading since single biopsies may not have sampled the most aggressive tumour area. Finally, investigators think that PROGENY will reveal how prostate cancers evolve over time and which of these changes lead to metastases and ultimately kill the patient. These are called phylogenetic studies and will help work out the main (or 'trunk') genomic changes from later events in 'branches'. This may allow researchers to focus their drug discovery efforts on the common 'trunk' genomic changes.