RESUMEN
BACKGROUND: Gastrointestinal cancers, including esophageal, gastric, liver and pancreatic are relatively common in Iran. Furthermore, consumption of opium and its derivatives (O&D) are considerable. This study, aimed to examine the association between consumption of O&D and the incidence of upper gastrointestinal (UGI) cancers. METHODS: In a matched case-control study in Kerman (located in southeast of Iran), 142 patients with UGI cancers and 284 healthy people (matched in terms of age, sex and residence (urban/rural)) were recruited. Variables (using O&D, smoking, alcohol use and diet) were collected using a structured questionnaire. Conditional logistic regression models were used to assess the above mentioned association. RESULTS: Opium use was associated with an increased risk of UGI cancers with an adjusted OR 4.0 (95% CI=2.2-7.0). A very strong dose-response relation was observed between consumption of O&D and the incidence of UGI cancers. (Three consumption levels-none, low and high; OR=18.7; 95% CI=5.5-63.3). This dose-response relationship was also strong even in patients with gastric cancers (OR=9.2; 95% CI=2.5-33.7). CONCLUSION: The results of this study showed that opium consumption can be a strong risk factor for UGI cancers in Iran.