Detection of TMPRSS2-ETS Fusions by a Multiprobe Fluorescence in Situ Hybridization Assay for the Early Diagnosis of Prostate Cancer : A Pilot Study

Fusion of the prostate-specific and androgen-regulated transmembrane-serine protease gene (TMPRSS2) with the erythroblast transformation-specific (ETS) family members is the most common genetic alteration in prostate cancer. However, the biological and clinical role of TMPRSS2-ETS fusions in prostate cancer, especially in problematic prostate needle core biopsies, has not been rigorously evaluated. We randomly collected 85 specimens including 50 archival prostate cancer tissue blocks, 15 normal prostate specimens, and 20 benign prostatic hyperplasia specimens for TMPRSS2-ETS fusion analyses. Moreover, the fusion status in an additional 20 patients with initial negative biopsies who progressed to biopsy-positive prostate cancer at subsequent follow-ups was also characterized. Fluorescently labeled probes specific for ERG-related rearrangements involving the TMPRSS2-ERG fusion as well as TMPRSS2-ETV1 and TMPRSS2-ETV4 were used to assess samples for gene rearrangements indicative of malignancy under a design of sequential trial. Rearrangements involving TMPRSS2-ETS fusions were detected in 90.0% of the 50 postoperative prostate cancer samples. The positive rate for the rearrangements in the initial prostate cancer-negative biopsies of 20 patients who eventually progressed to prostate cancer was 60.0% (12/20). Our preliminary study demonstrates that the clinical utility of TMPRSS2-ETS fusion detection as a biomarker and ancillary diagnostic tool for the early diagnosis of prostate cancer is promising, given this approach shows significant high sensitivity and specificity in detection.