PTEN and Familial prostate cancer: However, in contrast with de Bono’s data, Punnoose demonstrated that PTEN loss, analyzed by both blood-based PTEN fluorescence in situ hybridation (FISH) assay in circulating tumor cells and IHC, correlates with a poorer clinal outcome in castration-resistant prostate cancer, possibly due, at least in part, to the small sample size used [121].