Early-onset metastatic and clinically advanced prostate cancer is a distinct clinical and molecular entity characterized by increased TMPRSS2–ERG fusions

Background: Men with early-onset prostate cancer are at increased risk for cancer-related mortality, yet the prevalence and spectrum of molecular alterations in this patient population is unknown. Here, we analyze comprehensive genomic profiling data to characterize the molecular drivers of early-onset prostate cancer in patients with clinically advanced and metastatic disease. Methods: Next-generation sequencing was ordered as a part of routine clinical care for 10,189 patients with prostate cancer between 02/2013 and 03/2020 using commercially available comprehensive genomic profiling. Results: Deidentified genomic data for 10,189 unique patients with prostate cancer were obtained (median age = 66 y, range = 34–90 y). 439 patients were ≤50 y (4.3%), 1928 patients were between ages of 51 and 59 y (18.9%), and 7822 patients were ≥60 y (76.8%). Of metastatic biopsy sites, lymph node, liver, and bone were the most common in all groups, accounting for 60.2% of all specimens. Overall, 97.4% of patients harbored pathologic genomic alterations. The most commonly altered genes were TP53, TMPRSS2–ERG, PTEN, AR, MYC, MLL2, RAD21, BRCA2, APC, SPOP, PIK3CA, RB1, MLL3, CDK12, ATM, and CTNNB1. Patients ≤50 y harbored significantly more TMPRSS2–ERG fusions than patients ≥60 y, while AR copy number alterations as well as SPOP and ASXL1 mutations were significantly less frequent. Conclusions: Clinically advanced and metastatic early-onset prostate cancer is a distinct clinical subgroup with characteristic genomic alterations including increased frequency of TMPRSS2–ERG fusions and fewer AR, SPOP, and ASXL1 alterations.