Purpose of review Prostate cancer is a disease of the elderly but a clinically relevant subset occurs early in life. In the current review, we discuss recent findings and the current understanding of the molecular underpinnings associated with early-onset prostate cancer (PCa) and the evidence supporting age-specific differences in the cancer genomes. Recent findings Recent surveys of PCa patient cohorts have provided novel age-dependent links between germline and somatic aberrations which points to differences in the molecular cause and treatment options. Summary Identifying the earliest molecular alterations in PCa can provide insight into the cause of the disease and biomarkers for patient risk stratification. Genomic aberrations of early-onset PCas display several patterns distinct from late-onset PCa genomes, suggesting age-dependent pathomechanisms involving alterations in the androgen receptor pathway.