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

食道癌是肯尼亚男性和女性的第三大常见癌症和癌症死亡原因，2012年有3000多名新诊断患者。这种模式在其他东非国家很常见，而肯尼亚西部似乎有极高的发病率。这一情况与西非大部分地区形成了鲜明对比，那里的癌症极其罕见，即低40倍。可悲的是，这些患者中的大多数在确诊后6个月内去世，很少有人能够负担得起有限的治疗选择。此外，多达15%的患者非常年轻，在20多岁和30多岁之间。尽管研究人员从20世纪50年代就知道了这种不寻常的疾病模式，但在2014年之前，几乎没有人研究过这种疾病的风险因素。因此，没有针对性的战略来预防这种疾病，也没有预测模型来确定谁可能是这种疾病的高危人群，哪些人可能会从早期发现中受益。2014年，我们--即肯尼亚莫伊大学的Diana Menya博士--在肯尼亚开始了第一项关于生活方式、环境和遗传因素的全面研究。这项研究是在埃尔多雷特的莫伊教学和转诊医院进行的，该医院为延伸到乌干达边境的集水区人口提供服务。在这项研究中，新诊断为食道癌的患者与医院患者和没有患上这种疾病的医院访客进行了比较。研究人员还收集了血液和肿瘤样本进行遗传分析。这项研究的结果表明，酒精和烟草会导致老年男性患上这种疾病，但对女性或年轻患者没有影响。这项研究希望通过门亚博士和利物浦大学家庭空气污染专家丹尼尔·波普博士在英国和肯尼亚的合作来填补这一知识空白。这项研究假设，在通风不佳的厨房里使用生物质做饭造成的家庭空气污染，通过与烹饪相关的传统家务角色，是年轻人和女性患食道癌的主要原因。来自生物质和煤炭使用的家庭空气污染已经是一种公认的肺癌致癌物质，但很少有研究研究它对食道癌的影响。然而，在伊朗食道癌发病率较高的地区进行的研究表明，在这种情况下，燃烧生物质燃料后形成的化合物与食道癌风险有关。在这次英国与肯尼亚的合作中，我们建议继续之前成功实施的核心研究，并在此基础上增加一个深入的组成部分，即在厨房测量的家庭空气污染，以及在家访中对居住在转诊医院范围内的女性和年轻(40岁)参与者的个人暴露。将提供家庭空气污染对食道癌风险的详细分析，最后，考虑到一系列生活方式和环境风险因素，将编写一份关于肯尼亚食道癌初级预防所需战略的综合报告。这种疾病在世界许多地区的发病率已经下降--肯尼亚应该能够跟随这一趋势。

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.