Cancer of the esophagus is one of the most frequently diagnosed cancers in parts of East Africa, yet this cancer is extremely rare in West Africa. West Kenya, a region at altitude in Africa's Rift Valley, is one of East Africa's endemic areas. Typically patients are diagnosed at very late stages, and most die within months. No large-scale studies have been conducted to systematically investigate the potential causes of this cancer. Building on a successfully conducted pilot case-control study in which esophageal cancer patients are compared to non-cancer patients, we propose to continue and expand this study to investigate potential risk factors for the disease. Risk factors are obtained through interviews with participants, and include information on alcohol, tobacco, exposures to indoor pollution and hot beverage drinking. We also aim to investigate a novel hypothesis that deficiencies of some minerals in the diet may contribute to this disease in this area. The co-location of the East African esophageal cancer belt with the African rift valley suggest the dietary deficiencies may play a role as the diet is locally-source and cereal/plant based. Dietary deficiencies are difficult to evaluate in esophageal cancer patients, as patients have typically lost considerable weight by the time of diagnosis so urine and blood levels of vitamins and minerals are affected by their disease. As household members often have very similar diets, we will evaluate whether nutrient levels in such a household member can be used to approximate the patient's levels usual nutrient levels before they were ill. The factors being studied are all modifiable, thus if they are found to be causes of esophageal cancer in West Kenya, interventions could be implemented to remove exposures to carcinogens (e.g. advice on alcohol intake, particularly stronger spirits), or through fortification of fertilizers.
Esophageal cancer is exceptionally common in East Africa, and in particular in West Kenya. We will study whether esophageal cancer in this area is due to factors such as local alcoholic brews, smoking, air pollution from wood/charcoal burning, hot drinks and dietary deficiencies especially of essential micronutrients. The results will identify which of these modifiable factors need to be targeted to reduce the burden of extremely poor- prognosis cancer.
