Dietary factors and esophageal cancer in the Caspian Littoral of Iran.

A study was undertaken to attempt to relate the distribution of exogenous factors to the varying incidences of esophageal cancer in the Caspian Littoral of Iran. For the study, 38 villages were chosen by random sampling in 14 regions defined by their esophageal cancer incidence and environmental characteristics. Information was obtained on the dietary, social, and cultural features of each village. In addition, an extensive 5-day study of 6 randomly selected households in each of the 38 villages was conducted. The study consisted of measured dietary intake, a historical food consumption questionnaire, and clinical examinations of adult occupants. Preliminary results show no single factor responsible for the etiology of esophageal cancer. However, there were some major dietary differences between the regions of different esophageal cancer risk. Bread was the chief staple food in high-incidence areas; rice, in low-incidence areas. In high-incidence areas, there was a low intake of vitamins A and C, riboflavin, animal protein, and fresh vegetables and fruit, but a greater consumption of sheeps and goat's milk. Analyses of food samples for aflatoxins, polycylic aromatic hydrocarbons, and nitrosamines showed low levels of these carcinogens in areas of high and low incidences. The use of tobacco and alcohol was not found to be of significance.