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Human Pathology (2013) xx, xxx–xxx

Original contribution

The prognostic role of ERG immunopositivity in prostaticacinar adenocarcinoma: a study including 454 cases andreview of the literature☆,☆☆

Bin Xu MD, PhDa,1, Myriam Chevarie-Davis MD, MSc a,1, Simone Chevalier PhDb,Eleanora Scarlata PhDb, Nebras Zeizafoun MDc, Alice Dragomir PhDb,Simon Tanguay MDb, Wassim Kassouf MDb, Armen Aprikian MDb, Fadi Brimo MDa,⁎

aDepartment of Pathology, McGill University Health Center, Montreal, CanadabDepartment of Urology, McGill University Health Center, Montreal, CanadacDepartment of Pathology, St Luke's Roosevelt Hospital Center, New York, NY, USA

Received 3 September 2013; revised 4 October 2013; accepted 10 October 2013

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Keywords:ERG;TMPRSS2/ERG fusion;Immunohistochemistry;Prostate adenocarcinoma;Biochemical recurrence

Summary TMPRSS2/ERG fusion is among the most frequent genetic anomalies in prostateadenocarcinomas. Although positive immunostaining for ERG has been shown to tightly correlatewith ERG fusion status, the clinical and prognostic significance of a positive ERG stain remainsundetermined. The significance of ERG immunostaining in 454 consecutive prostate adenocarcinomasfrom radical prostatectomies (RPs) using tissue microarrays, herein, is evaluated. A separate set of 59cases of incidental prostate adenocarcinoma detected on transurethral resection of prostate with aGleason score of 6 was also included. ERG translocation was significantly more common inperipheral zone cancer in comparison with cancer of the transitional zone (33% in RP versus 5% intransurethral resection of prostate specimens). In the RP cohort, although ERG positivity wassignificantly associated with younger age at presentation and lower prostate-specific antigen values, itshowed no association with Gleason score or with pathologic stage. In multivariate analysis,biochemical recurrence was only associated with the final RP Gleason score and elevated prostate-specific antigen levels and was unrelated to neither ERG positivity or to its staining intensity. In ourhands, ERG positivity was unrelated to either aggressive local tumor characteristics or a worseoutcome. Our results, as well as an extensive review of the related literature showing conflictingfindings, seem to indicate that ERG immunopositivity cannot be considered as an importantprognostic factor in prostate cancer.© 2013 Elsevier Inc. All rights reserved.

☆ Disclosure and conflict of interests: All contributing authors herebycknowledge the responsibility for the work presented in this manuscriptnd declare no potential conflicts of interests.

☆☆ Funding sources: None.⁎ Corresponding author. Department of Pathology, Montreal General

ospital, Montreal, Quebec, Canada H3G 1A4.E-mail address: fadi.brimo@muhc.mcgill.ca (F. Brimo).1 Both authors contributed equally to the study.

046-8177/$ – see front matter © 2013 Elsevier Inc. All rights reserved.ttp://dx.doi.org/10.1016/j.humpath.2013.10.012

1. Introduction

Prostate cancer is the most prevalent cancer and thesecond leading cause of cancer death in men world-wide, with an incidence of 206 640 and a mortality of

2 B. Xu et al.

28 088 in the United States [1]. In 2005, Tomlins et al[2] discovered a recurrent chromosome fusion inprostate cancer, involving the androgen-regulated trans-membrane protease serine 2 (TMPRSS2) on chromosome21q22.3 and erythroblast transformation–specific (ETS)regulated gene-1 (ERG) on chromosome 21q22.2,making it the first discovered translocation in thiscancer. Since then, numerous studies have confirmedthat TMPRSS2/ERG fusion is the most common geneticevent in prostate cancer, with a reported prevalence of~50% in radical prostatectomy (RP) and biopsyspecimens [3-24] and ~20% in incidental tumors fromtransurethral resection of prostate (TURP) specimens[4,5,13,25-30]. It has also been reported to be presentin a minority of cases of high-grade prostate intrae-pithelial neoplasia [3,31-33].

ERG is an oncogene that belongs to the ETS familyof transcription factors, which play an important role inregulating cell proliferation, differentiation, apoptosis,and angiogenesis [34,35]. The TMPRSS2/ERG fusionresults in an aberrant expression of a truncated ERGproduct, which can be detected reliably using ERGimmunohistochemistry (IHC). The use of IHC as asurrogate method to detect TMPRSS2/ERG fusion hasbeen previously validated in several large-scale studieswith a reported sensitivity of 95.7% to 100% and aspecificity of 85% to 99% compared with the criterionstandard methods, namely, fluorescent in situ hybridiza-tion (FISH) or reverse transcription polymerase chainreaction (RT-PCR) [6,9,22,29,36,37]. Using FISH, PCR,RT-PCR, and/or IHC techniques, more than 14 000prostate cancer cases have been investigated in multiplestudies in an effort to establish the diagnostic andprognostic values of TMPRSS2/ERG fusion in prostatecancer. However, the results were conflicting, reportinga positive [4,5,11,17,18,26,30,31,38-49], null [4,7,8,10-12,15-18,20,22,26,27,30,38,40,42-47,49-75], or negative[12,15,20,28,42,45,47,50,54,55,59,62,76] association be-tween TMPRSS2/ERG fusion and aggressive clinicopath-ologic parameters including preoperative prostate-specificantigen (PSA) levels, Gleason score, pathologic stage,biochemical recurrence (BCR), and disease-specificmortality.

In an effort to clarify the prognostic value of a positiveERG immunostain in prostate adenocarcinoma, the immu-nopositivity of ERG in a large cohort of 454 cases obtainedfrom RP specimens was evaluated herein, and the ERGimmunoreactivity was correlated with a variety of clinico-pathologic parameters. In addition, we included a separateset of 59 cases of incidental transitional zone adenocarcino-ma detected on TURP specimens to compare the prevalenceof ERG immunoreactivity between peripheral zone andtransitional zone cancers. A comprehensive review of therelated literature was also undertaken, the results of whichare compared with the current study and are presented in thecurrent report.

2. Materials and methods

2.1. Characteristics of the patients and tissuemicroarray construction

Eight tissue microarrays (TMAs) were constructed usingtissues obtained from the surgical pathology archives of theMcGill University Health Centre (Montreal, Quebec,Canada). The TMAs included 454 consecutive RPs contain-ing prostate acinar adenocarcinoma performed between 1993and 2008. Most prostatectomies were sampled, in theirentirety, for histologic examination. The hematoxylin andeosin slides were retrieved and reviewed by a genitourinaryexpert pathologist (F.B.) at the time of TMA construction toconfirm the Gleason score using the current/modifiedgrading system, surgical margin status, and the AmericanJoint Committee on Cancer (AJCC) pathologic stage [77].Each tumor was represented by 2 separate 1-mm cores toaccount for potential intratumoral heterogeneity. The coreswere taken from the representative area of the dominantnodule. In cases in which the dominant nodule had a lowerGleason score than the secondary nodule, the secondarynodule with the highest Gleason score was also sampled toensure that the core Gleason score reflected the final score ofa given case. To provide adequate negative immunohisto-chemical control, 62 cores of randomly selected areas ofbenign prostatic and renal parenchyma were included in theTMA blocks. An additional set of 59 cases of incidentaltransitional zone adenocarcinoma, detected in TURP spec-imens with a Gleason score of 6 and an overall tumor volumeof less than 1% (pT1a), was also included.

Among the 454 patients who underwent RP, 297 patientshad detailed clinical follow-up with a follow-up duration of5.6 ± 0.2 years (mean ± SEM). The Gleason score,pathologic stage, surgical margins status, and ERG positivitywere compatible between patients with and without clinicalfollow-up (data not shown). The primary clinical outcomestudied was BCR, which is defined as a PSA level of 0.4 ng/mL or higher post-RP.

2.2. Immunohistochemistry

IHC was performed using a Ventana automated systemand Ventana Iview DAB detection kit (Ventana MedicalSystems Inc, Tucson, AZ). A monoclonal mouse antihumanERG antibody (Clone 9FY; Biocare Medical LLC, Concord,CA), with a dilution of 1:100, was used. The evaluation ofimmunostaining was performed by the participating pathol-ogist blinded to the outcome. A case was considered positivefor ERG whenever nuclear staining of tumor cells wasidentified in at least 1 core regardless of its intensity. Inaddition, the intensity of nuclear staining was evaluatedsemiquantitatively using a 4-tiered system as follows: 0,negative; 1, weak staining; 2, moderate staining; and 3,intense staining (Fig. 1).

3ERG immunopositivity in prostate adenocarcinoma

2.3. Statistical analysis

All analyses were performed using the Statistical AnalysisSystem Software (version 9.3; SAS Institute, Cary, NC), andall tests were 2 sided, with a significance threshold of 5%. AStudent t test was used to examine the correlation of ERGstatus and clinical characteristics, for example, age atpresentation and preoperative PSA level. A Pearson χ2 testor a Fisher exact test was performed to correlate the ERGimmunopositivity with BCR, or local tumor characteristics,including AJCC staging (pT or pN) and Gleason score. Theoutcome start point was the date of surgery, whereas theoutcome end point was the date of the last follow-up orBCR.Amultivariate analysis was performed using the Cox propor-tional hazards model to evaluate the association between BCRand prognostic factors including the following: Gleason score,status of surgical margin, and ERG immunopositivity.Separate statistical analyses were performed to study theassociation of ERG staining intensity with clinicopathologiccharacteristics and BCR, which yielded very similar statisticalresults (data not shown). Therefore, only results based on ERGpositivity and negativity are reported in the current article.

3. Results

3.1. Clinicopathologic characteristics and ERGimmunopositivity in RP and TURP

The clinical and pathologic characteristics of the RP cohortare summarized in Table 1. In brief, a total of 454 patients wereincluded in the current study, with an age of 60.7 ± 0.3 years(mean ± SEM) at the time of surgery and a mean preoperativePSA of 8.0 ± 0.4 ng/mL. The most common total Gleasonscore reported in this cohort was 7 (3 + 4 or 4 + 3), accountingfor 62.3% of cases (n = 283). The rest of cases had a Gleasonscore of 6 (n = 133 [29.3%]), 8 (4 + 4, n = 28 [6.2%]), or 9 (n =10 [2.2%]). Most patients (n = 266 [58.6%]) had organ-confined disease (AJCC pT2), whereas 127 patients (28.0%)

Fig. 1 Representative images of ERG IHC in prostate adenocarcinoma1 (B, weak), 2 (C, moderate), and 3 (D, strong).

had extraprostatic extension (AJCC pT3). Sixty-one patients(13.4%) had positive surgical margins in areas of intraprostaticincision (pT2+). Among the 188 patients with lymph nodesampling at the time of radical prostectomy, 3 patients (1.6%)had metastasis to regional lymph nodes (pN1). Of the 297patients with available clinical follow-up of 5.6 ± 0.2 years(mean ± SEM), 80 patients (26.9%) recurred after a meanduration of 2.8 years.

Among the 454 RP specimens, 151 adenocarcinomas(33.3%) demonstrated ERG immunoreactivity including thefollowing: 75 cases (16.5%) with weak, 50 cases (11.0%)with moderate, and 26 cases (5.7%) with strong stainingintensity. The ERG IHC yielded a homogenous stainingpattern in all cores examined, with a compatible stainingintensity among cores taken from the same case. Cauteryartifact that was sometimes encountered in TURP specimensdid not alter the ERG immunostaining in neoplastic orendothelial cells. In comparison, the prevalence of ERGimmunopositivity in incidental adenocarcinoma detected inTURP specimens was significantly lower, with only 3 (5.1%)of 59 cases showing ERG immunopositivity (χ2 test, P b.0001). The 62 cores of benign prostate and renalparenchyma were all negative for the marker.

3.2. ERG immunopositivity in relation toclinicopathologic characteristics

The clinical and pathologic features of ERG-negative andERG-positive prostatic adenocarcinomas are shown inTable 1. Compared with ERG-negative cases, ERG-positivecases were associated with a significantly younger age atdiagnosis (2-tailed Student t test, P = .002) and a lowerpreoperative PSA level (2-tailed Student t test, P = .03). Incontrast, ERG immunoreactivity appeared to have noinfluence on BCR (Pearson χ2 test, P = .66) or local tumoralcharacteristics. The Gleason score and pathologic stage werecomparable between the 2 groups (Pearson χ2 test, P = .69for Gleason score, and P = .45 for AJCC pT stage; Fisherexact test, P = .55).

(×400). The intensity of nuclear staining is scored as 0 (A negative),

Table 1 The association of ERG immunoreactivity and clinicopathologic characteristics of prostatic adenocarcinoma in RP

All ERG negative ERG positive P

n (%) 454 303 (66.7) 151 (33.3)Age at diagnosis (y), mean ± SEM 60.7 ± 0.3 a 61.4 ± 0.3 59.5 ± 0.5 .002 a

Preoperative PSA (ng/mL), mean ± SEM 8.0 ± 0.4 a 8.5 ± 0.6 7.0 ± 0.6 .03 a

Duration of follow-up (y), mean ± SEM 5.6 ± 0.2 a 5.4 ± 0.2 5.8 ± 0.4 .36 a

Gleason score, n (%)3 + 3 133 (29.3) 89 (29.4) 44 (29.1) .69 b

3 + 4/4 + 3 283 (62.3) 185 (61.1) 98 (64.9)4 + 4 28 (6.2) 22 (7.3) 6 (4.0)4 + 5/5 + 4 10 (2.2) 7 (2.3) 3 (2.0)AJCC pT stage, n (%)pT2 266 (58.6) 179 (59.1) 87 (57.6) .45 b

pT2+ 61 (13.4) 43 (14.2) 18 (11.9)pT3a 106 (23.4) 65 (21.5) 41 (27.2)pT3b 21 (4.6) 16 (5.3) 5 (3.3)Lymph node sampling (n = 188), n (%)pN0 185 (98.4) 67 (100) 118 (97.5) .55 c

pN1 3 (1.6) 0 (0) 3 (2.5)BCR (n = 297), n (%)No 217 (73) 71 (74.7) 146 (72.3) .66 b

Yes 80 (27) 24 (25.3) 56 (27.7)a Two-tailed Student t test.b Pearson χ2 test.c Fisher exact test.

4 B. Xu et al.

3.3. ERG expression in relation to BCR

To determinate the potential prognostic role of ERG, amultivariate analysis using the Cox proportional hazardsmodel was performed. BCR was only associated with higherGleason score (hazards ratio, 4.30; 95% confidence interval[CI], 1.78-10.40; P = .001) and elevated preoperative PSAlevels (hazards ratio, 1.03; 95% CI, 1.00-1.05; P = .04). Nosignificant correlation was detected between BCR and age atthe time of diagnosis (hazards ratio, 0.99; 95% CI, 0.95-1.03;P = .47), surgical margin status (hazards ratio, 1.39; 95% CI,0.86-2.24;P = .18), or ERG immunopositivity (hazards ratio =1.04; 95% CI = 0.63-1.71; P = .88). A Kaplan-Meier curverevealed no difference in terms of BCR-free survival betweenERG-positive and ERG-negative groups (Fig. 2).

ig. 2 Kaplan-Meier curve of disease-free survival: the expres-ion of ERG is unrelated to BCR.

4. Discussion

TMPRSS2 and ERG genes are located 3 Mb apart onchromosome 21q. Under the influence of androgens,intrachromosomal interstitial deletion or translocation oc-curs, leading to juxtaposition of the androgen-responsiveTMPRSS2 gene to the transcription unit of ERG [78,79].TMPRSS2/ERG fusion produces a truncated ERG protein,which, in turn, mediates transcription, apoptosis, cellproliferation, differentiation, and invasiveness via multiplemolecular pathways [78-80]. The molecular targets, whichhave been shown to interact with ERG, include the

following: poly(ADP-ribosome) polymerase 1 [81], DNAprotein kinase [81], HDAC1 target genes and WNT/β-catenin signaling pathway [82], matrix metaloproteinases,PIM-1 oncogene, c-MYC oncogene, PI3K-PTEN axis, andEZH2 polycomb group protein [78-80]. Recently, it has beenshown that poly(ADP-ribosome) polymerase 1 inhibitorselectively represses the growth of ERG-positive, but notERG-negative, prostate cancer xenografts, renderingTMPRSS2/ERG fusion a potential molecular therapeutictarget for prostate cancer [81].

The reported incidence of TMPRSS2/ERG fusion inprostate adenocarcinoma ranges from 20% to 68% in RPand biopsy specimens [3-24] and from 0 to 29% in incidentaltumors detected in TURP specimens [4,5,13,25-30]. This

Fs

Table 2 Association of TMPRSS2/ERG fusion or ERGoverexpression with clinicopathologic characteristics:a summary of English literature

Association of ERG fusion with No. of studies No. of men

Preoperative PSALow level 6 6159High level 2 510No association 20 2740Gleason scoreLow score 8 5424High score 9 1734No association 37 6455Pathologic stageLow stage 0 0High stage 10 5540No association 35 6474Recurrence and/or mortalityLow risk 1 150High risk 8 1078No association 30 11 092Total 54 14 376

5ERG immunopositivity in prostate adenocarcinoma

wide range of incidence is influenced by multiple factorsincluding study design, detection methods (PCR, FISH, orIHC), patients' ethnic background, intratumoral immunohe-terogeneity of ERG, interobserver and interstudy variability ofstain interpretation, the clone of the ERG antibody used, andthe molecular difference between transitional and peripheralzone tumors [11,13,24,50-52,76,83-85]. Our study included59 cases of prostatic adenocarcinoma detected in TURPspecimen. Only cancers with a total Gleason score of 6 and anoverall tumor volume of less than 1% of TURP volume wereincluded in an effort to ensure that the adenocarcinoma wereof transitional zone origin rather than an extension of prostaticcancer from the peripheral zone. Consistent with what hasbeen previously reported, we have found that the incidence ofERG immunopositivity in RP (151/454 patients; 33%) wassignificantly higher compared with that of incidental transi-tional zone cancers detected in TURP specimens (3/59patients; 5.1%). The exact significance of such a zonaldifference in terms of ERG expression is unclear, but mostlikely reflects the biological difference between transitionaland peripheral zone cancers [24,84,85].

The main objective of the current study was to investigatewhether ERG immunopositivity was associated with clinicaland pathologic phenotypes of prostate adenocarcinoma, andwhether it could serve as a prognostic biomarker to predictrecurrence and mortality. Numerous studies have beenpublished, in the past decade, which generated conflictingresults. We have reviewed all available English literature,from 2005 to 2013, that focused on the association betweenTMPRSS2/ERG fusion/ERG overexpression in RPs and thefollowing 4 clinicopathologic parameters: (1) preoperativePSA level, (2) Gleason score, (3) AJCC pathologic stage,and (4) recurrence and mortality. Tumor stage, Gleasongrade, and PSA level were selected because they are the 3criteria currently used by clinicians following the D'Amicocriteria to define prognostic risk groups and to guidetreatment [86]. A total of 56 studies [4,5,7,8,10-12,15-18,20,22,26-28,30,31,38,38-76] including 14 571 men withprostate cancer were identified, and the results are summa-rized in Table 2. Details of each study, in terms of the numberof patients, detection methods for ERG, and specimen type(RP, TURP, or biopsy), are provided in Table 3.

The result of this literature review shows that ERG-positive prostate cancer cases tend to have a lowerpreoperative PSA level compared with ERG-negativecases. A total of 6 studies, with 6159 men, including the 4largest-scale studies to date with 481, 1039, 1180, and 2805men [15,54,56,58] and the present study with 454 men, haveshown a significant correlation of ERG positivity with lowPSA levels. In contrast, 20 studies [7,10,11,17,18,20,40,42-45,49-51,56-61], with a samples size of 19 to 254, havereported no correlation between ERG status and PSA level,which might be explained by a lack of statistical power dueto small sample size.

Based on the existing evidence, we cannot conclude, withconfidence, the relationship between ERG status and

Gleason score. Eight studies of 5424 prostate cancers[12,28,42,47,50,55,59,62,76] have reported a significantnegative association; 9 studies of 1734 men [4,5,11,26,39-41,43,44] reported a positive association, and 37 studies of6455 men, including our own, reported a null associationbetween ERG status and high Gleason score [7,8,10,15-17,20,22,27,30,38,38,44,45,45,46,49,51-54,56-61,63-71].

Overall, TMPRSS2/ERG fusion tends to be associated withadvanced AJCC pathologic stage. Ten studies, including 5540men [4,11,30,31,39,42,45,45-47], have found a higherpercentage of advanced disease in ERG-positive cancercompared with ERG-negative cancer, whereas the reversehas not been reported in the literature. The link between ERGpositivity and advanced tumor stage has been further supportedby a meta-analysis across 34 studies and 8003 RPs, in whichTMPRSS2/ERG fusion was associated with more advancedpathologic stage at diagnosis [45]. However, such associationis not always clear-cut. Thirty-five studies of 6474 men[7,8,10,12,15,17,18,20,22,26,27,38,38,40,44,49-51,54,56-58,60-62,64-70,72], including the current study, have shownthat ERG status was independent from pathologic stage.Possible explanations could be that the adverse correlationbetween ERG and tumor stage is biologically trivial, or onlypresent in a small subset of patients. Therefore, suchassociation cannot be readily detected in small-scale studies.

Despite the high prevalence of TMPRSS2/ERG fusion inprostate adenocarcinoma, the fusion carries very little, if any,prognostic value in predicting BCR and cancer-specific death.Overwhelming evidence from 30 studies and 11 092 men[4,7,8,12,15,38,43,44,44-47,50,53-56,58,60-65,67,70,73-75],including the present study, has demonstrated that ERGpositivity was unrelated to recurrence or mortality. Thisconclusion was further supported by the meta-analysis

Table 3 Association of TMPRSS2/ERG fusion or ERGoverexpression with clinicopathologic characteristics:a detailed review of literature

Reference N Assay Type

Low PSA level (6 studies, 6159 men)[54] a 200 FISH Bx

454 IHC RP[15] 481 IHC RP[55] 1039 IHC RP[45] 1180 IHC RP[47] 2805 IHC RPHigh PSA level (2 studies, 510 men)[38] 65 FISH RP[39] 445 FISH RPNo association with PSA level (20 studies, 2740 men)[40] 19 IHC RP[18] 26 RT-PCR RP[44] 45 RT-PCR RP[56] 45 RT-PCR RP[57] 50 FISH RP, TURP[10] 59 FISH RP[45] 90 IHC TURP[49] 122 FISH RP[20] 150 FISH RP[51] 150 FISH RP[7] 163 FISH RP[17] 165 RT-PCR RP[58] 178 FISH Bx[42] 184 TLDA RP[59] 194 RT-PCR RP[43] 197 FISH, RT-PCR RP[11] 209 IHC RP, Bx[60] 214 FISH RP, TURP[61] 226 RT-PCR RP[50] 254 FISH RPLow Gleason score (8 studies, 5424 men)[76] 174 FISH RP[42] 184 TLDA RP[59] 194 RT-PCR RP[62] 253 IHC RP[50] 254 FISH RP[12,28] 521 FISH RP[55] 1039 IHC RP[47] 2805 IHC RPHigh Gleason score (9 studies, 1734 men)[40] 19 IHC RP[41] 75 FISH RP[5] 105 FISH TURP[26] 111 FISH, PCR TURP[43] 197 FISH, RT-PCR RP[11] 209 IHC RP, Bx[44] 261 IHC RP[4] 312 IHC TURP[39] 445 FISH RPNo association with Gleason score (37 studies, 6455 men)[22] 41 IHC, PCR RP[38] 42 FISH RP[44] 45 RT-PCR RP[56] 45 RT-PCR RP

Table 3 (continued)

Reference N Assay Type

[57] 50 FISH RP, TURP[63] 50 RT-PCR RP[30] 54 FISH TURP[64] 54 RT-PCR, FISH RP[10] 59 FISH RP[65] 59 RT-PCR RP[38] 65 FISH RP[66] 82 FISH, RT-PCR RP[67] 84 RT-PCR RP[53] 85 RT-PCR Mets[68] 88 FISH, RT-PCR RP[45] 90 IHC TURP[27] 94 FISH RP[16] 100 FISH Bx[46] 118 FISH RP[49] 122 FISH RP[69] 147 IHC RP[20] 150 FISH RP[51] 150 FISH RP[70] 158 RT-PCR Bx[7] 163 FISH RP[17] 165 RT-PCR RP[58] 178 FISH Bx[71] 180 IHC, FISH RP[59] 194 RT-PCR RP[54] 200 FISH Bx[60] 214 FISH RP, TURP[61] 226 RT-PCR RP[52] 248 FISH RPa 454 IHC RP[15] 481 IHC RP[8] 540 FISH RP[45] 1180 IHC RPLow AJCC stage (0 study)High AJCC stage (10 studies, 5540 men)[30] 54 FISH TURP[45] 90 IHC TURP[46] 118 FISH RP[31] 143 IHC, FISH RP[42] 184 TLDA RP[11] 209 IHC RP, Bx[4] 312 IHC TURP[39] 445 FISH RP[45] 1180 IHC RP[47] 2805 IHC RPNo association with stage (35 studies, 6474 men)[40] 19 IHC RP[18] 26 RT-PCR RP[22] 41 IHC, PCR RP[38] 42 FISH RP[44] 45 RT-PCR RP[56] 45 RT-PCR RP[57] 50 FISH RP, TURP[64] 54 RT-PCR, FISH RP[10] 59 FISH RP[65] 59 RT-PCR RP[38] 65 FISH RP

6 B. Xu et al.

Table 3 (continued)

Reference N Assay Type

[66] 82 FISH, RT-PCR RP[67] 84 RT-PCR RP[68] 88 FISH, RT-PCR RP[27] 94 FISH RP[72] 95 FISH RP[26] 111 FISH, PCR TURP[49] 122 FISH RP[69] 147 IHC RP[20] 150 FISH RP[51] 150 FISH RP[70] 158 RT-PCR Bx[7] 163 FISH RP[17] 165 RT-PCR RP[58] 178 FISH Bx[54] 200 FISH Bx[60] 214 FISH RP, TURP[61] 226 RT-PCR RP[62] 253 IHC RP[50] 254 FISH RPa 454 IHC RP[15] 481 IHC RP[12] 521 FISH RP[8] 540 FISH RP[55] 1039 IHC RPLow risk of recurrence or mortality (1 study, 150 men)[20] 150 FISH RPHigh risk of recurrence or mortality (8 studies, 1078 men)[40] 19 IHC RP[18] 26 RT-PCR RP[45] 90 IHC TURP[48] 100 IHC RP[26] 111 FISH, PCR TURP[49] 122 FISH RP[17] 165 RT-PCR RP[39] 445 FISH RPNo association with clinical outcome (30 studies, 11 092 men)[44] 45 RT-PCR RP[56] 45 RT-PCR RP[63] 50 RT-PCR RP[64] 54 RT-PCR, FISH RP[65] 59 RT-PCR RP[38] 65 FISH RP[73] 67 RT-PCR RP, TURP[67] 84 RT-PCR RP[53] 85 RT-PCR Mets[46] 118 FISH RP[70] 158 RT-PCR Bx[7] 163 FISH RP[58] 178 FISH Bx[43] 197 FISH, RT-PCR RP[54] 200 FISH Bx[60] 214 FISH RP, TURP[61] 226 RT-PCR RP[62] 253 IHC RP[50] 254 FISH RP[44] 261 IHC RP[4] 312 IHC TURP

Table 3 (continued)

Reference N Assay Type

[74] 344 FISH RPa 454 IHC RP[15] 481 IHC RP[12] 521 FISH RP[8] 540 FISH RP[75] 640 FISH RP[55] 1039 IHC RP[45] 1180 IHC RP[47] 2805 IHC RP

Abbreviations: Bx, biopsy; Mets, metastasis; RP, radical prostatectomy;TURP, transurethral resection of prostate; Type, type of the specimen; FISH,fluorescence in situ hybridization; IHC, immunohistochemistry; RT-PCR,real-time polymerase chain reaction; TLDA, TaqMan low-density arrays.

a Current study.

7ERG immunopositivity in prostate adenocarcinoma

performed by Pettersson et al [45] across 19 studies and 5074prostate cancers. Once again, conflicting evidence has beenreported, with 8 studies (1078 men) [17,18,26,39,40,45,48,49]showing a positive association and 1 study (150 men) [20]showing a negative association between ERG fusion and anadverse clinical outcome.

Other than reporting ERG staining in prostate cancer aspositive or negative, only 2 studies, to date, have evaluated theprognostic value of the intensity of ERG staining, which yieldconflicting results [4,48]. Bismar et al [4] have shown anegative correlation between staining intensity and cancer-specific mortality, whereas Spencer et al [48] reported anincreased risk of BCR, metastasis, and cancer-specific death inprostatic cancer with high ERG intensity. In our hands, therewas no association between staining intensity or H-score on onehand and any clinicopathologic or outcome parameters onanother hand.

In summary, the biological relationship betweenTMPRSS2/ERG fusion and clinicopathologic parameters,such as PSA level, Gleason score, pathologic stage, andprognosis, is not well established, and the results of differentstudies lack consistency. That being said, the possibility thatERG status may only influence a small subset of prostatecancer cases bearing a unique histologic or molecularsignature exists, and such a relationship would be dilutedwhen all prostate cancers are pooled into different studies.Further studies incorporating thorough morphologic andimmunophenotypic features, or using advanced moleculartechniques (eg, array-comparative genomic hybridizationand next-generation sequencing) to allow the comparison ofgene profiles, will be required to identify the subgroup ofprostate cancers in which TMPRSS2/ERG fusion may beprognostically important.

5. Conclusions

In this TMA study of 454 prostate adenocarcinomas fromRP and 59 incidental cancers from TURP, we have found

8 B. Xu et al.

that ERG overexpression was much more common inperipheral zone prostate cancers in comparison with thoseof the transitional zone. In our hands, ERG immunopositivitywas unrelated either to aggressive local tumor characteristicsor to a worse outcome.

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