The overall goal of this project is to determine whether polycyclic aromatic hydrocarbons (PAHs) or acetaldehyde are contributing to the high rate of esophageal cancer in Linxian, China.

Esophageal cancer is one of the most fatal cancers worldwide with Linxian, China having one of the highest rates in the world. In the United States esophageal cancer causes approximately 14,000 deaths each year. It is the fourth most common cause of cancer death in black males and the eighth leading cause of cancer death in men of all races. The prevention and treatment of esophageal cancer within high risk groups continues to be limited by our inability to identify specific etiologic agents.

Human exposure to PAHs, including benzo[a]pyrene (B[a]P), is associated with an increased rate of skin, lung, and upper GI tumors and also with an increased mortality from causes related to atherosclerosis. Preliminary results from histologic and food analysis pilot studies, supports the possibility that the high rates of esophageal cancer in Linax may be related to long-term, high-level exposure to PAHs via inhalation of air-borne pollution and ingestion of food cooked with soft coal.

Exposure to acetaldehyde could also be an etiologically significant exposure in Linxian. Acetaldehyde is a carcinogenic metabolite, and small quantities of ethanol were recently found in homogenized Linxian food samples. The Salaspuro laboratory at the University of Helsinki has demonstrated that oral bacteria can produce acetaldehyde from food containing similar small concentrations of ethanol, so such acetaldehyde exposure could be etiologically significant in Linxian Genetic polymorphisms, particularly those involving alcohol and acetaldehyde dehydrogenases, may also influence the effect of this exposure.

To assess the association of PAHs and acetaldehyde with the high rate of esophageal cancer in Linxian, China, we plan to analyze samples of food for the presence of PAHs, ethanol and acetaldehyde, samples of blood for Hb adducts (markers of long-term PAH or acetaldehyde exposure), samples of urine for 1-OH-Pyrene glucuronide (a maker of short-term PAH exposure), samples of saliva for acetaldehyde and samples of coal for characteristics that may be associated with increased carcinogenesis. We will also administer environmental questionnaires that will include questions about the type of fuel used for cooking and heating, the location and type of stove and/or heating units, and time spent cooking.