TMPRSS2-ERG Fusions Unexpectedly Identified in Men Initially Diagnosed With Nonprostatic Malignancies

PurposeTMPRSS2-ERG gene fusions are frequently found in prostate cancer and are pathognomonic for prostatic origin. In a series of cancer cases assayed with comprehensive genomic profiling (CGP) in the course of clinical care, we reviewed the frequency of TMPRSS2-ERG fusions in patient tumors of various histologic subtypes.MethodsFrequency of TMPRSS2-ERG fusions was determined in CGPs from 64,263 cancer cases submitted to Foundation Medicine to assess genomic alterations suggesting benefit from targeted therapy. Genomic results are presented from an index case of prostate cancer that underwent evolution from adenocarcinoma to pure squamous cell carcinoma.ResultsTMPRSS2-ERG fusions were identified for 0.86% of male patients (250 of 29,030) and not found for female patients (none of 35,233). TMPRSS2-ERG fusions were detected in six tumors classified as squamous carcinoma, five of which were of unknown primary site. The index case is a patient with a large, left retrovesical mass diagnosed as squamous carcin...