There is a relevant study that demonstrated a polymorphism of cytochrome P450 family 2 subfamily E member 1 (CYP2E1), which is associated with NPC susceptibility, and it was found to upregulate the activation of pro-carcinogens, including nitrosamines that found in tobacco, salted and preserved food [31]. The gene discussed is CYP2E1; the disease is nasopharyngeal carcinoma.