Oesophageal cancer in Golestan Province, a high-incidence area in northern Iran - a review.

Golestan Province, located in the south-east littoral of the Caspian Sea in northern Iran, has one of the highest rates of oesophageal cancer (OC) in the world. We review the epidemiologic studies that have investigated the epidemiologic patterns and causes of OC in this area and provide some suggestions for further studies. Oesophageal squamous cell carcinoma (OSCC) constitutes over 90% of all OC cases in Golestan. In retrospective studies, cigarettes and hookah smoking, nass use (a chewing tobacco product), opium consumption, hot tea drinking, poor oral health, low intake of fresh fruit and vegetables, and low socioeconomic status have been associated with higher risk of OSCC in Golestan. However, the association of tobacco with OSCC in this area is not as strong as that seen in Western countries. Alcohol is consumed by a very small percentage of the population and is not a risk factor for OSCC in this area. Other factors, such as polycyclic aromatic hydrocarbons, N-nitroso compounds, drinking water contaminants, infections, food contamination with mycotoxins, and genetic factors merit further investigation as risk factors for OSCC in Golestan. An ongoing cohort study in this area is an important resource for studying some of these factors and also for confirming the previously found associations.