[856] Detection of ERG in Japanese Transition Zone Prostate Cancer

Bungo Furusato, Hiroyuki Takahashi, Takahiro Kimura, Jun Miki, Sainosuke Mizukami, Mioko Okayasu, Toshihiro Yamamoto, Hidetoshi Kuruma, Shin Egawa, Hiroshi Hano. The Jikei University School of Medicine, Tokyo, Japan

Background: Incidence of transition zone-prostate cancer (TZ-PCa) is relatively common in Japan. Gene fusion involving the ERG oncogene is a frequent alteration in prostate cancer (PCa) and studies from the Western countries have suggested that ERG expression is less common in TZ-PCa than in peripheral zone-prostate cancer (PZ-PCa). Here, we assessed the ERG expression in Japanese PCa by zonal origin and compared with clinicopathological parameters to see whether any differences exist between Japan and the Western countries.
Design: We evaluated 92 index tumors from Japanese patients who had undergone radical prostatectomy for PCa, using an antibody-based detection method to determine ERG expression. Expression status was compared with clinicopathological findings including zonal origin of index tumor (TZ, PZ, or both), tumor size, Gleason score, pathological stage and Body mass index (BMI).
Results: In 92 cases, the index tumor distribution was 42.4% (39/92), 32.6% (30/92) and 25% (23/92) in PZ, TZ, and both zones, respectively. Overall, ERG expression was detected in 16.3% (15/92) of the cases. Among the ERG positive cases, 73.3% (11/15) were detected in PZ-PCa, 20% (3/15) were detected in TZ-PCa and 6.7% (1/15) were detected in tumor located in both zones. ERG expression was associated with Gleason score in PZ-PCa (p=0.01) and TZ-PCa (marginally, p=0.046). There was no association between ERG expression and rest of the parameters including tumor size, pathological stage and BMI in both TZ- and PZ-PCa's.
Conclusions: Although there are significant differences in the rate of overall ERG expression between Japan (16.3%) and Western PCa's (50%), there is a similar trend of ERG expression in TZ-PCa from both countries. The lower frequency of ERG expression in TZ-PCa may be a common trend among Western and Aisan (Japan) countries, which may suggest distinct molecular alterations from PZ-PCa. Therefore, further studies are required to determine whether this finding is reproducible in multi-institutional analysis to better understand differences in molecular profiles between PZ- and TZ-PCa's.
Category: Genitourinary (including renal tumors)

Monday, March 19, 2012 1:00 PM

Poster Session II # 157, Monday Afternoon


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