epidemiology of oral cavity cancers in a country located in the esophageal cancer belt: a case control study

introduction: as one of the most common cancers among head and neck malignancies, cancer of the oral cavity probably has some variations in countries with a high prevalence of esophageal cancer.  materials and methods: patients with oral cavity cancer who were treated at two tertiary referral centers from january 1999 to january 2009 were included in this study. in addition to demographic data, information regarding personal and family history of head and neck cancer, use of dentures, presence of immune deficiency, consumption of alcohol, and incidence of cigarette smoking was collected. additionally, a history of opium usage was obtained from the participants in this study. moreover, an appropriately matched control group was selected for comparisons between the risk factors.   results: a total of 557 patients were entered into this study over a 10-year period, of whom 219 (39.3%) were female and the remaining 338 (60.7%) were male. the tongue was the most common site of cancer and 9% of the patients had a history of opium abuse, but more than half of the patients did not have any recognized risk factors. the incidence and stage of cancer had a significant relationship with cigarette smoking (p= 0.013).   conclusion: tongue cancer in non-smokers is the predominant pattern of oral cavity cancer in iran.