CYP2A6, CYP2B6, CYP2C9, CYP2D6, CYP2E1, and CYP3A4/5 had higher Vmax values in HCC patients, while the Vmax values of CYP1A2 and CYP2C8 were significantly reduced relative to control samples. This evidence concerns the gene CYP2A6 and hepatocellular carcinoma.