title: Carcinogenesis as a multistage process--evidence from human studies.
mesh_terms: D003043:Cocarcinogenesis; D006801:Humans; D008175:Lung Neoplasms / Q000209:etiology; D009369:Neoplasms / Q000209:etiology*; D014801:Vitamin A / Q000502:physiology
chemical_list: D014801:Vitamin A