Vitamin D Deficiency in High and Low Risk Populations for Esophageal Cancer in Northern Iran

Background: Diverse relationships have been proposed between esophageal cancer (EC) and vitamin D serum levels. We aimed to assess serum levels of vitamin D in high and low-risk populations for EC in Northern Iran. Methods: This ecological study was conducted in Golestan province, Northern Iran. Based on the incidence rates of EC, the province was divided into high-risk and low-risk populations. A stratified cluster sampling method was used. Serum vitamin D levels were assessed using the ELISA method. The proportions of vitamin D deficiency were compared between the two populations. Results: A total of 246 persons were studied, with a mean age of 50.7 years. 96 subjects were male (39%) and 146 subjects were female (61%). 119 subjects (48.8%) were from high-risk and 127 (51.6%) were from low-risk populations. Thirty-two of 244 (13.1%) persons had vitamin D deficiency. The proportions of vitamin D deficiency were 7.9% and 18.3% in highand low-risk populations, respectively (p=0.02). Conclusion: We found that significantly larger numbers of people suffered from vitamin D deficiency in populations at low-risk of EC compared to high-risk populations. Regarding the ecological design of this study, causal inference could not be made from our results. Therefore, we recommend further investigation of this issue in future individual-level studies in this area, and in other high-risk populations.