TMPRSS2-ERG gene fusion is associated with low Gleason scores and not with high grade morphologic features

摘要

TMPRSS2-ERG gene rearrangement is seen in about half of clinically-localized prostate cancers, yet controversy exists regarding its prognostic implications. Similarly, the relationship of TMPRSS2-ERG fusion to Gleason score and morphology remains uncertain. We assigned Gleason scores and recorded morphologic features for 521 clinically-localized prostate cancers sampled in triplicate and arrayed in 8 tissue microarray blocks. Fluorescence in situ hybridization was performed to delineate TMPRSS2-ERG aberrations. Using maximum Gleason score, based on 3 core evaluation, and overall Gleason score, based on prostatectomy sections, Fisher’s exact test was performed for tumors with TMPRSS2-ERG translocation/deletion, copy number increase (≥3) of the TMPRSS2-ERG region without translocation/deletion, and copy number increase and concomitant translocation/deletion. 217 (41%) translocation/deletion and 30 (5.9%) copy number increase alone cases were detected. Among 217 translocation/deletion cases, 32 had translocation/deletion with copy number increase. 237, 200, and 75 cancers had maximum core-specific Gleason score of 6, 7, and 8–10, respectively. Tumors with translocation/deletion tended toward lower Gleason scores than those without (p=0.002) with similar results for overall Gleason score (p=0.02); Copy number increase cases tended toward higher Gleason scores than those without (p<0.001). Gleason score 8–10 tumors demonstrated lower odds of translocation/deletion (OR 0.38; 95%CI 0.21–0.68) and higher odds of copy number increase alone (OR 7.33; 95%CI 2.65–20.31) or copy number increase + translocation/deletion (OR 3.03; 95%CI 1.12–8.15) relative to Gleason score < 7 tumors. No significant difference in TMPRSS2-ERG incidence was observed between patients with and without cribriform glands, glomerulations, signet ring cells, or intraductal cancer (p=0.821, 0.095, 0.132, 0.375). TMPRSS2-ERG gene fusion is associated with lower core-specific and overall Gleason scores and not with high grade morphologies. Conversely, TMPRSS2-ERG copy number increase, with or without rearrangement, is associated with higher Gleason score. These findings indicate that translocation/deletion of TMPRSS2-ERG is not associated with histologic features of aggressive prostate cancer.