Trial Information

The Golestan Cohort Study of Esophageal Cancer

Esophageal cancer is the sixth most common cause of cancer death worldwide, killing over
380,000 people each year. Over 80% of esophageal cancers occur in developing countries,
where the great majority of cases are squamous cell carcinomas. Esophageal cancer is
characterized by striking geographic variation in incidence. One remarkable high-risk area,
called the Central Asian Esophageal Cancer Belt, stretches from the Caspian Sea across
Central Asia to northern China and includes focal areas with recorded incidence rates
greater than 100/10s/year in both genders. For the past 20 years, D CEG investigators have
studied esophageal and gastric cancer in one of these extremely high-risk areas, Linxian,
China, at the eastern end of the Belt. While these studies have discovered new risk factors
for esophageal cancer in this region, they have produced an incomplete explanation of the
etiology of this disease. Now we have the opportunity to perform similar studies in another
of these extremely high-risk areas, Golestan Province, Iran, at the other end of the
high-risk Belt. The people of Golestan, in northeastern Iran, are geographically, culturally
and ethnically quite different from the people of Linxian, and they appear to be similar
only in their extraordinarily high rates of esophageal cancer. Performing similar studies in
these two exceptional populations will give us a better chance to identify important new
modifiable risk factors for esophageal cancer in both places.

Our cohort study is a collaboration between the Digestive Disease Research Center of Tehran
University of Medical Sciences (DDRC), the International Agency for Research on Cancer
(IARC), and DCEG. The study has recruited 50,000 adults in three administrative districts of
eastern Golestan Province. Baseline assessments included lifestyle questionnaire, a
semi-quantitative food frequency questionnaire, and collection of blood, hair, nails and
urine. Follow up will includes active surveillance by a study team, aided by a comprehensive
health network in the rural areas, a GI referral clinic in the largest town, and a
provincial cancer registry. The main hypotheses include dietary hypotheses (low consumption
of fruits and vegetables, high consumption of hot tea), exposure to potential carcinogens
(tobacco, PAHs from non-tobacco sources), novel exposures (opium, animal contact), and
genetic susceptibility. Some cross sectional and a few total mortality analyses have been
completed. Annual follow-up is ongoing.