[941] Clinicopathological Correlation of ERG Protein Expression in Single Focus Prostate Cancer.

Isabell A Sesterhenn, Shyh-Han Tan, Albert Dobi, Shiv Srivastava, David G McLeod, Stephen A Brassell, Bungo Furusato. Armed Forces Institute of Pathology, Washington, DC; Uniformed Services University of the Health Sciences, Bethesda, MD; Walter Reed Army Medical Center, Washington, DC

Background: A single cross section of a cohort of 132 whole mount radical prostatectomies were previously stained with an ERG antibody developed in the Center for Prostate Disease Research revealed either positive or negative tumors. The purpose of this study was to determine by immunohistochemistry if single large prostatic carcinomas are homogeneous with respect to their ERG oncoprotein expression status despite their heterogeneous appearance in the H&E stained sections.
Design: In 14 (10.6%) of the 132 specimens a single tumor was identified. Laterality, zone of origin, tumor volume, Gleason score, and pathologic stage were recorded. Eight of these were utilized for immunohistochemical evaluation of the entire tumors. Following deparaffinization and antigen retrieval the sections were incubated with the ERG MAb at a dilution of 1:1280 followed by biotinylated horse anti-mouse antibody at a dilution of 1:200 (Vector Laboratories, Burlingame, CA, USA) followed by treatment with the ABC Kit (Vector Laboratories) The color detection was achieved by treatment with VIP (Vector Laboratories).
Results: Patient's median age was 61 years and median PSA was 5.2 ng/mL. Single focus cancers were unilateral in five of eight cases and all five cases were located in the peripheral zone. The median tumor volume was 7.2 cc. (range: 2 cc. to 18.8 cc.) Gleason score (Gl) distribution was: Gl 7 (3+4) in four of eight, and Gl 8-10 in three of eight cases. One case consisted of a minute focus of carcinoma, too small to give Gleason score. Pathological stage was pT2 in three of eight, pT2 R1 in one of eight and pT3/4 in four of eight cases. ERG expression was detected in all tumors. Six of eight cases showed intratumoral heterogeneity. The other two cases showed homogeneous ERG expression.
Conclusions: Although the number of cases is small, the results suggest that the ERG expression correlates with either a single or multiple clonal origin of prostatic carcinoma in these high volume, and high-grade tumors.
Category: Genitourinary (including renal tumors)

Monday, February 28, 2011 1:00 PM

Poster Session II # 110, Monday Afternoon


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