Quantitative proteomics studies comparing primary tumors to benign tissue (Table 1) describe a number of DEPs which have been identified between PCa and non-malignant tissue from the same patient [59], PCa and benign prostatic hyperplasia (BPH) [50,53,56], low-risk and high-risk prostate cancer groups [46], low- and high-grade prostate cancer [51], different ISUP grades [50], and even laser-capture microdissection (LCM)-isolated cellular fractions, such as epithelial cells of different Gleason grade [48] or ERG status [60]. This evidence concerns the gene ERG and prostate cancer.