ERG and prostate cancer: In 2017, an investigation of 10,945 advanced tumors sequenced with MSK-IMPACT described genomic rearrangements in 15% of tumors tested; the most commonly identified were: TMPRSS2-ERG (n = 151; exclusive to prostate cancer), EML4-ALK (n = 38), and EWSR1-FLI1 (n = 25; exclusive to Ewing sarcoma).14 Of the gene fusions identified, 35% (n = 268) involved kinase genes and encompassed all or part of the kinase domain, most commonly:14ALK (n = 42), BRAF (n = 33), RET (n = 32), ROS1 (n = 29), FGFR2 (n = 27), and FGFR3 (n = 23) (Fig. 2).