Household air pollution, polycyclic aromatic hydrocarbons and esophageal cancer risk in Kenya: ESCCAPE case-control study

Background and Aim Esophageal squamous cell carcinoma (ESCC) is highly prevalent in Western Kenya. Established risk factors (e.g. smoking and alcohol consumption) are not common in female patients. Exposure to household air pollution (HAP) from solid fuels used for cooking and heating might be relevant in ESCC aetiology. As such, this study aims to examine the relationship between self-reported indicators of exposure to HAP with risk of ESCC in Western Kenya. Methods Six-hundred and four (604) ESCC cases and six-hundred and thirty-one (631) controls were recruited during three phases of the ESCCAPE Kenya case-control study. Surveys on risk factors were conducted with all participants. Surveys included questions on demographic and socio-economic factors, and fuels used in the home currently and during childhood, and their proximity to heating and cooking sources. Results When accounting for confounding demographic factors, odds ratios (OR) derived from binomial regression illustrates a significantly increased risk of esophageal cancer among those who use firewood as their primary cooking fuel (OR: 2.187; CI: 1.368-3.557). Women were almost three times as likely to have esophageal cancer when using firewood as the primary cooking fuel (OR: 2.821; CI: 1.255-6.917). Risk of esophageal cancer was significantly greater among participants who cooked in their living room (OR: 1.954; CI: 1.234-3.107). Findings demonstrate greater wood burning exposure is associated with significantly heightened risk of esophageal cancer. Conclusions Findings from the ESCCAPE case-control study indicate the potential role of exposure to smoke from firewood used in cooking and heating, in the complex aetiology of ESCC. Given the increased lifetime exposure to woodsmoke for women due to traditional domestic roles, and their lower exposure to other known risk factors, reliance on solid fuels for domestic energy could be an important potentially preventable risk factor for women in areas when the occurrence of ESCC is high.