CYP2A6 and neoplasm: In GSE14520 dataset, we identified the fact that low expressions of four CYPs including CYP2A6, CYP2C8, CYP2E1, and CYP4A11 in tumor tissues were significantly associated with worse OS in HCC patients (log ranks P = 0.01, 0.006, 0.024, and 0.007, respectively, Figure 3).