Risk factors of esophageal cancer in Turkmen Sahra of Iran

Esophageal cancer is the fourth cancer of digestive system that constitutes two up to five percent of all identified malignancies (1). One of the main characteristics of this lethal disease is its specific geographical distribution. For instance, its incidence has been reported to be 3/100,000 in Europe and USA (2). However, this is in some parts of central Asia, which is known as esophageal cancer belt including Turkmen Sahra of Iran and China have been reported to be 115/100,000 and 130/100,000, respectively (2,3). Esophageal cancer in the north east of Iran, (Turkmen Sahra in Golestan Province) was reported to be 165 and 195/100,000 for females and males, during 1980s (4-12). Furthermore, in 1995 the number of registered esophageal cancer cases in Mazanderan province was reported to be 115 that denoted 28% of total of the district and 56% of the whole esophageal cancers of the country (13). When Golestan in northeast of Mazanderan was announced as a new province in 1996 with the total population of 1,466,289 comprising 710,287 men and 716,001 women, the docuABSTRACT