esophageal cancer in iran: a review

esophageal cancer is the second and third most common malignancy in iranian males and females, respectively, claiming lives of approximately 5800 iranians each year. squamous cell carcinoma (scc) is presently the most common type accounting for about 90% of all esophageal cancers in iran. recent studies have shown that there is a gradual increase in the incidence of adenocarcinoma of the distal esophagus along with gastric cardia adenocarcinoma. thirty-five years ago, the age standardizied rate (asr) of esophageal scc in the city of gonbad (golestan province, northeast of iran) was found to be one of the highest rates for any single cancer that had been reported worldwide (asr >100/105/year). recent studies have shown that the incidence of scc in gonbad has declined to less than half of what it was in the past. this decline in the incidence of esophageal scc parallels an improvement in the socioeconomic situation of people living in this region. according to recent cancer registry data in iran there is still an obvious intracountry variability between the incidence of esophageal cancer in the south with an asr of 3 for males and 2 for females in kerman and 43 and 36 in the northeastern province of golestan. the reasons for this very high rate of scc in northeastern iran have been the subject of several studies during the past 35 years. according to results of these studies the suspected risk factors are: low intake of fruits and vegetables, drinking hot tea, consumption of opium products and tobacco, h.pylori infection in the stomach, using unhealthy drinking water from cisterns and genetic susceptibility. the main suspected mutagens are polycyclic aromatic hydrocarbons (pah) and n-nitroso compounds. in order to embark primary and secondary prevention of this fatal cancer, further prospective studies are presently underway in the region. the golestan esophageal cancer cohort study which follows of 50,000 subjects is on going. we expect simple and feasible evidence based preventive strategies to be implemented in the future according to the results of this study.