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Biomarkers of Exposure to Combustion Products Associated with Esophageal Cancer

, by Jennifer K. Loukissas, M.P.P.

photograph of a cooking stove with smoke from burning wood

Smoke from burning wood contains carcinogenic compounds.

Researchers from the Metabolic Epidemiology Branch (MEB), in collaboration with the Centers for Disease Control and Prevention (CDC) and with funding from the Food and Drug Administration (FDA), have identified urinary biomarkers of exposure to by-products of combustion that were associated with elevated risk of esophageal cancer in a region with uniquely high rates of this often-fatal malignancy. The findings were published on October 24, 2023, in the Journal of the National Cancer Institute.

Worldwide, esophageal cancer is the eighth most common cancer and the sixth leading cause of cancer death because of its poor prognosis. While tobacco is a leading cause, in high-incidence areas, known as the “Asian esophageal cancer belt,” other factors may make greater contributions to risk. 

Arash Etemadi, M.D., Ph.D., staff scientist in MEB, and colleagues, investigated urinary biomarkers of exposure to polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs) in a population of predominantly never-users of tobacco. Samples were collected many years prior to diagnosis. 

These findings provide evidence for an association between esophageal cancer and exposure to PAHs and VOCs, byproducts of incomplete combustion resulting from tobacco smoke but also present in air pollution and fumes from fuel, cooking, heating, and other sources. Many of these chemicals are classified by the International Agency for Research on Cancer as probable or possible carcinogens based on laboratory or animal evidence but limited epidemiologic data. 

These novel associations were identified using individual-level data and urine samples collected many years before cancer incidence. The assays were conducted by laboratories at the CDC and with funding from the FDA Center for Tobacco Products. Results confirm the carcinogenic role of nicotine metabolites in esophageal cancer and demonstrate the importance of many other smoke-related exposures, particularly among non-users of tobacco products. More strict monitoring and control of these exposures resulting from burning organic material, as well as household and industrial products and food additives, could help to reduce risk for this malignancy.


Etemadi A et al. Exposure to polycyclic aromatic hydrocarbons, volatile organic compounds, and tobacco-specific nitrosamines and incidence of esophageal cancerJ Natl Cancer Inst. 2023.