In this context, methylation data from both TCGA (Human 450K BeadChip; PCa, n = 451; adjacent non-tumor tissues, n = 50) and GEO (PCa, n = 219; control tissues, n = 169) were analyzed to re-evaluate the diagnostic performance of previously reported prostate cancer-associated differentially methylated genes (DMGs), including APC, CCND2, GSTP1, PRKY, and RASSF1. The gene discussed is APC; the disease is prostate cancer.