Array-based genomic analysis of screen-detected Gleason score 6 and 7 prostatic adenocarcinomas

Prostate cancer is known for its heterogeneous histological appearance. It is currently not clear whether this histological heterogeneity is also reflected in the genomic composition of a tumor.

The cancer DNA's were retrieved from the European Randomized Study of Screening for Prostate Cancer section Rotterdam (ERSPC). Tumors with volumes 1.0-1.5 ml and a Gleason score of 3+3 or 3+4 were selected. Comparative genomic hybridization with a 3500-element BAC array was used to detect differences in the genetic content of Gleason patterns 3 and 4.

A total of 1155 gains and 583 losses were discriminated in 10 G3 areas; 768 gains and 497 losses were detected in 7 G4 regions. Frequent losses included chromosome arms 6q, 8p and 13q, while frequent gains were seen on 7q and 8q. There were no significant differences between Gleason patterns 3 and 4, or between Gleason grades within one cancer.

Histological heterogeneity, defined by Gleason grades 3 and 4, does not have a genomic counterpart. Furthermore, these asymptomatic screen-detected prostate carcinomas have genetic signatures comparable with those commonly seen in symptomatic cancers.