Marked Increase in the Incidence Rate of Esophageal Adenocarcinoma in a High-risk Area for Esophageal Cancer

Esophageal cancer (EC) is the eighth common cancer worldwide. Esophageal squamous cell carcinoma (ESCC) and adenocarcinoma (EAD) are the most common histologic types of EC. Many recent reports showed an increasing trend in EAD and a decreasing trend in ESCC in many Western countries. Golestan Province in northeastern Iran has been known as a high-risk area for EC. The aim of this study was to describe the time trend of EAD in this area between 2000–2009. Data on cancer cases were obtained from Golestan Population-based Cancer Registry. Analysis was done using Joinpoint software. To examine the incidence trends, the annual percent change was calculated. The possibilities of anatomic and histologic misclassification were considered by assessing the trend of ESCC and gastric adenocarcinoma. A total number of 1186 histologically-confirmed EC cases were recruited. The incidence rate of EAD showed a significant increasing trend. There was no significant trend in the incidence of ESCC during the study period. A significant increase in the incidence rate of gastric adenocarcinoma was observed during the period of 2000–2005, followed by a plateau during the period of 2005–2009. We found a significant increasing trend in the incidence rate of EAD. We find no evidence to support an alternative explanation including anatomic and histologic misclassification. So, the observed rise in the incidence of EAD seems to be real. Therefore, designing and implementation of control programs, including control of preventable risk factors of EAD, should be considered in this high- risk area.