To identify methylation alterations associated with PCa aggressiveness, we used a discovery cohort of 70 PCa cases (Table 1) with good (organ-confined disease and lack of recurrence for at least 5 years) or poor prognosis (systemic presence of metastatic disease, indicated by biochemical PSA-based recurrence within 3 years and no response to local radiation therapy) for genome-wide methylation analyses using Illumina 450k arrays. The gene discussed is KLK3; the disease is metastatic neoplasm.