Association of PTEN protein loss with upgrading of prostate cancer from biopsy to radical prostatectomy.

127 Background: Active surveillance is increasingly recommended for men with low-risk Gleason Score 3+3=6 (GS 6) prostate cancer. Yet, approximately one-third of patients with GS 6 cancer on biopsy are upgraded to higher GS at radical prostatectomy (RP). Previous studies have shown that clinical-pathologic parameters (age, prostate-specific antigen [PSA], prostate volume, extent of disease) are weak predictors of GS6 tumor upgrade. Our goal was to investigate the utility of PTEN as a molecular marker to predict upgrading in GS 6 biopsies. Methods: In a retrospective case-control study, 71 patients with GS 6 tumors on needle biopsy that were upgraded to GS 7 or higher cancer at RP (cases) were compared to 103 patients whose GS 6 tumors on needle biopsy were not upgraded at RP (controls). The most extensively involved needle core biopsy from each case was immunostained and scored for PTEN protein loss using a previously validated immunohistochemical (IHC) assay and binary scoring system. Confirmatory fluore...