[999] Variation of ERG Oncoprotein Expression in Prostate Cancer Patients of Different Ethnicities

Gyorgy Petrovics, Molly Williams, Sudhir Rawal, Philip Rosen, David Pfister, Takahiro Inoue, Takehiko Segawa, Osamu Ogawa, Monica Colombo, Yongmei Chen, Denise Young, Albert Dobi, David G McLeod, Isabell Sesterhenn, Shiv Srivastava. Center for Prostate Disease Research, Rockville, MD; Walter Reed National Military Medical Center, Bethesda, MD; Rajiv Gandhi Cancer Institute, New Delhi, India; Institute of Pathology, Aachen, Germany; Kyoto University Graduate School of Medicine, Kyoto, Japan; Joint Pathology Center, Silver Spring, MD

Background: ERG gene fusions leading to ERG overexpression represent a highly prevalent oncogenic alteration (50-70%) in prostate cancer (CaP) patients of Caucasian ethnicity. A lower ERG frequency in CaP of African Americans (AA) in comparison to Caucasian Americans (CA) was noted. There is no study of ERG alterations in CaP patients from India. This comparative study of the frequency of ERG oncoprotein expression focused on CaP patients with Asian (India, Japan), AA and CA ethnicity.
Design: Archived FFPE blocks from radical prostatectomy specimens (RP) of 51 patients from the Rajiv Gandhi Cancer Institute, New Delhi, India, were analyzed for the presence of ERG oncoprotein by immunohistochemistry (IHC) using the ERG monoclonal antibody (ERG MAb, 9FY). From Japan, tissue microarray (TMA) derived from RP of 64 patients (160 cancer spots) with localized CaP was analyzed by the same anti-ERG Mab. A USA cohort of RP assessing ERG in multifocal tumor context from 91 AA and 91 CA CaP patients (matched for age, Gleason score and pathologic stage) was analyzed.
Results: Of 30 evaluable specimens from India, 8 cases (27%) had ERG positive tumors. Of 64 Japanese patients, 16 (25%) had at least one ERG positive TMA spot. No correlation between ERG status and Gleason score or PSA failure was found. In systematic evaluation of whole mounted RP, the frequency of ERG positive tumors was significantly greater in CA than AA men assessing all tumor foci (41.9% vs. 23.9%, p<0.0001) or in index tumors (63.3% vs. 28.6%, p<0.0001).
Conclusions: Frequency of ERG oncoprotein expression is much lower in CaP patients with Asian (25-27%) or African (28%) descent than in patients with European descent (63%). This study underscores that ERG typing of CaP, may enhance our understanding of biological differences between ethnic groups.
Category: Genitourinary (including renal tumors)

Monday, March 4, 2013 1:00 PM

Poster Session II # 147, Monday Afternoon


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