Golestan Province in northern Iran is a very high-incidence area for oesophageal squamous cell carcinoma (OSCC), while tobacco and alcohol use, the major risk factors of OSCC in the Western countries, are not common habits there. As an attempt to indentify the risk factors of OSCC in Golestan, the following studies were conducted in the context of this thesis: a meta-analysis on Helicobacter pylori and risk of OSCC; a cross-sectional study on patterns of food and nutrient intake among 131 healthy individuals; a case-control study with 300 cases/571 controls on the association of socioeconomic status and tea drinking habits with OSCC; a cross-sectional study on patterns of exposure to polycyclic aromatic hydrocarbons (PAHs) among 110 healthy individuals. -- In the meta-analysis, there was no significant association between H. pylori and risk of OSCC, but there was substantial heterogeneity among studies. A large proportion of Golestan inhabitants drink hot tea. Our results showed a two-fold and 8-fold increase in risk of OSCC associated with drinking hot and very hot tea, respectively. Several indicators of SES, including formal education, being married, and high wealth were inversely associated with risk of OSCC. We found severe nutrient deficiencies among rural dwellers and women and a high exposure of the general population to PAHs in Golestan. Only kerosene and gas were used for heating, which was not associated with exposure to PAHs. Red meat intake, passive smoking, and certain genetic polymorphisms showed associations with PAH metabolites in urine. Meat frying intensity had significant associations with bulky DNA adduct levels. -- Interactions among several factors, e.g. hot tea drinking and intra-luminal PAHs, with the background of poor socioeconomic status and deficient nutrient intake, may be responsible for the high incidence of OSCC in Golestan.
Golestan Province in northern Iran is a very high-incidence area for oesophageal squamous cell carcinoma (OSCC), while tobacco and alcohol use, the major risk factors of OSCC in the Western countries, are not common habits there.
