CYP2C9 and esophageal cancer: Beside the well-known role in metabolizing and activating of pro-carcinogens, CYP2C9 seems to be relevant for early esophageal cancer development by promoting tumor cell proliferation (Schmelzle et al., 2011) and altered CYP2C9 metabolism may play a relevant role in lung carcinogenesis (García-Martín et al., 2002).