The north-eastern region of the Islamic Republic of Iran has some of the highest rates of esophageal cancer anywhere in the world. New results from an international prospective study of 50,000 individuals, recently published online in the journal Gastroenterology, provide evidence on how the combined effects of six main risk factors are responsible for the high rates of esophageal cancer in this region.
The results are based on more than 10 years of follow-up of 50,000 individuals as part of the Golestan Cohort Study, which was initiated in 2004 by the Digestive Diseases Research Institute of the Tehran University of Medical Sciences, the International Agency for Research on Cancer, and NCI.
The six most important risk factors identified were drinking hot tea, smoking opium, low intake of fruits and vegetables, drinking unpiped water, exposure to indoor air pollution, and excessive tooth loss.
The study found that about three quarters of the esophageal cancer cases in the north-eastern region can be attributed to a combination of exposures to the identified risk factors, which are all preventable through education and by improving basic social infrastructure.
The GCS is the largest prospective study of its kind in central and western Asia. It was established to provide a major resource for studying esophageal cancer, through the collection of biological samples and detailed assessments of diet, lifestyle, and different exposures, at enrolment and then every 5 years.
Instead of relying only on self-reported information, the GCS was the first study to also make objective measurements of the suspected risk factors for oesophageal cancer, including the actual temperature at which tea is drunk, and carry out precise oral examinations.
“The GCS was initiated in an area where esophageal cancer constituted about 25% of the reported cancer cases, and the study has made important contributions to the discovery and development of the scientific information on the risk factors for upper gastrointestinal cancers and other noncommunicable diseases,” Reza Malekzadeh, director of the Digestive Diseases Research Institute of the Tehran University of Medical Sciences and is the principal investigator of the GCS, said in a statement.
“The GCS represents a major and long-standing collaboration between scientists in the Islamic Republic of Iran, IARC, and NCI, and it is an important representation of how medical research can overcome political and economic barriers,” Paul Brennan, head of the Section of Genetics at IARC and is a co-principal investigator of the GCS, said in a statement.
“This study shows how the combination of the risk factors can substantially increase the risk of oesophageal cancer, and strongly suggests that esophageal cancer in high-incidence areas is a multifactorial disease, requiring a combination of exposures for its development. Therefore, this study has important implications for public health and policy, and will aid the translation of knowledge and the implementation of evidence into practice and policy decision-making.”
