title: Opium and oesophageal cancer in Iran.
mesh_terms: D002273:Carcinogens; D004938:Esophageal Neoplasms / Q000139:chemically induced*; D006801:Humans; D007492:Iran; D009892:Opium / Q000009:adverse effects*
chemical_list: D002273:Carcinogens; D009892:Opium