Household air pollution and risk of esophageal cancer: a case-control study in Western Kenya

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Esophageal cancer is the third most common cancer and cause of cancer death in both men and women in Kenya, with 3000+ newly diagnosed patients in 2012. This pattern is common to other East African countries and West Kenya appears to have extremely high rates of the disease. This status contrasts to much of West Africa where the cancer is extremely rare, i.e. 40 times lower. Sadly, the majority of these patients pass away within 6 months of their diagnosis, few being able to afford the limited treatment options. Additionally, up to 15% of patients are very young, in their 20s and 30s. Despite researchers having known about this unusual disease pattern since the 1950s, the risk factors for the disease had hardly been studied prior to 2014. Consequently, there are no targeted strategies to prevent the disease, and no prediction models to identify who might be at high risk of the disease, people whom may benefit from early detection.In 2014, we - i.e. the Kenya PI Dr Diana Menya of Moi University, Eldoret - commenced the first comprehensive study of lifestyle, environmental and genetic factors for esophageal cancer in Kenya. The study was conducted at the Moi Teaching and Referral Hospital, Eldoret, which serves a catchment population stretching to the Ugandan border. In the study, patients newly diagnosed with esophageal cancer were compared to hospital patients and hospital visitors who did not have the disease. The study blood and tumour samples were also collected for genetic analyses. Results from the study have shown that alcohol and tobacco contribute to the disease in older men, but not in women or in young patients, a knowledge gap which the present study hopes to fill through a UK-Kenya collaboration between Dr Menya and Dr Daniel Pope, a household air pollution expert from the University of Liverpool. This study hypothesizes that household air pollution, from using biomass for cooking in poorly ventilated kitchens, is a large contributor to esophageal cancer in the young and in women, through traditional domestic roles associated with cooking. Household air pollution from biomass and coal use is already an established lung carcinogen, but few studies have examined its influence on esophageal cancer. However, work in an Iranian area of high esophageal cancer rates has shown that chemical compounds formed after combustion of biomass fuels are implicated in esophageal cancer risk in that setting. In this UK-Kenya collaboration, we propose to continue the core study as previously successfully implemented, and add to it an in-depth component on household air pollution as measured in kitchens and for personal exposures during household visits to a subset of female and younger (< 40 years) participants who live within reach of the referral hospital. A detailed analysis of oesophageal cancer risk with household air pollution will be provided and finally, considering a range of lifestyle and environmental risk factors, a comprehensive report on the strategies needed for primary prevention esophageal cancer in Kenya will be developed. Rates of this disease have declined in many areas of the world - Kenya should be able to follow this trend.