GSTP1 and hepatocellular carcinoma: For 24 genes reported in at least three studies between HCC tumor tissues and adjacent tissues (Table 1), no evidence of statistical heterogeneity was observed for nine genes, including GSTP1 (I2 = 35%), PRDM2 (I2 = 40%), DAPK1 (I2 = 19%), p73 (I2 = 48%), hMLH1 (I2 = 0%), DLC1 (I2 = 0%), p53 (I2 = 16%), OPCML (I2 = 0%) and WT1 (I2 = 0%).