[856] TMPRSS2-ERG Gene Rearrangement in Prostate Cancers in the African American Population

A Gopalan, JM Satagopan, MA Leversha, HA Al-Ahmadie, SW Fine, SK Tickoo, JA Eastham, PT Scardino, M Koscuiszka, P Lee, I Osman, WL Gerald, VE Reuter. Memorial Sloan-Kettering Cancer Center, New York, NY; New York University, New York, NY

Background: Prior studies have demonstrated striking differences in the incidence and mortality rates from prostate cancer in African American (AA) men as compared to Caucasians, which are thought to be due to a combination of socioeconomic, cultural and poorly understood biological differences. Prior data from our institution suggested a low frequency of prostate tumors with high expression of ERG in AA versus white men. We also found that rearrangement was associated with lower grade cancers in a predominantly Caucasian cohort, which suggests that the frequency of cancers harboring the rearrangement and race-associated outcome might be related. Given the paucity of data in the literature about TMPRSS2-ERG gene rearrangement status in the AA population, we aimed to determine if there were distinct racial differences in the frequency of rearrangement-associated cancer.
Design: We evaluated TMPRSS2-ERG rearrangement status in 72 prostate cancers from AA men and a set of 43 Caucasian men by interphase FISH using a 3 color breakapart probe containing BAC clones against 3'ERG, 3' and 5' TMPRSS2.
Results: 6 of 64 evaluable tumors in AA (9%), and 11 of 38 evaluable tumors in Caucasians (29%) were positive for rearrangement (p=0.014). All rearrangement in AA was through interstitial deletion. In Caucasians, roughly two-thirds were rearrangement by deletion and the rest by translocation. There was no significant difference in Gleason score between AA and Caucasian men with the rearrangement. None of the AA patients with rearrangement had disease recurrence. Logistic regression analysis suggested that AA patients have a reduced probability of having disease recurrence in the presence of a rearrangement.
Conclusions: African American men have a significantly lower incidence of TMPRSS2-ERG gene rearranged prostate cancer. Rearrangement in this population occurs exclusively through interstitial deletion. Although the sample set is small, our data suggests that rearrangement is associated with a low probability of disease recurrence in African Americans. This preliminary data suggests that distinct molecular differences may play a role in the biological disparity seen in cancers in these ethnic populations.
Category: Genitourinary (including renal tumors)

Wednesday, March 24, 2010 1:00 PM

Poster Session VI # 131, Wednesday Afternoon

 

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