[876] Assessment of ERG Expression in Latent Prostate Cancer

Bungo Furusato, Hiroyuki Takahashi, Mioko Okayasu, Masato Kido, Takahiro Kimura, Shin Egawa, Masahiro Ikegami, Hiroshi Hano. Jikei University School of Medicine, Tokyo, Japan

Background: Prostatic carcinoma (PCa) is occasionally found at autopsy. The majority of those are thought to represent latent phase of the tumor. ERG gene rearrangements have been described in several cohorts as being the most common gene rearrangements in PCa. Many reports suggested that ERG expression was associated with aggressive tumor, although a few documented no such association. Thus, assessments of ERG expression in latent PCa may represent one of the best ways to address the association between ERG expression and biological aggressiveness of the tumor. In the current study, ERG expression in latent PCa was investigated to determine whether ERG rearrangements were involved in such silent phase of the tumor.
Design: The Jikei University institutional autopsy records between 2009 and 2011 were searched, and 104 autopsies that included prostate dissection were identified. We assessed ERG expression in these samples using immunohistochemistry and compared those expression patterns to pathological parameters, including grade and tumor volume.
Results: The prevalence of PCa detected at autopsy was 44.2%(46/104). The average tumor volume was 1280.02 mm3 (range: 0.5-19,091.2 mm3). 26.1% (12/46) of the cases examined had tumor volumes greater than 500 mm3; 73.9% (34/46) had tumor volumes less than 500 mm3. The tumor grade distribution was as follows: Gleason score of 5-6 (52.1%, 24/46), 7 (39.1%, 18/46) and 8-10 (8.7%, 4/46). Regarding tumor location, 34.8%(16/46), 63%(29/46) and 2.2%(1/46) were TZ, PZ and TZ+PZ, respectively. Overall, ERG expression was detected in 0 of 46 cases (0%), and this incidence differed from that of clinically detected prostate cancer (cf. 16%; our data from Japanese cases). One case showed cytoplasmic staining but we counted this as negative expression for ERG.
Conclusions: The lack of ERG expression in latent PCa may suggest that ERG rearrangement/expression is associated with adverse biological behavior. However, additional studies are warranted to substantiate the potential clinical value of ERG as a biomarker for clinically significant PCa.
Category: Genitourinary (including renal tumors)

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 70, Tuesday Morning


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