Environmental and Genetic Factors Causing Lung Cancer (Research Paper Sample)

Environmental and Genetic Factors on Lung Cancer
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Abstract
The battle against cancer would be far from being won if there was no research on the current risk factors of the chronic disease. Today, cancer ranks top among the leading death causes in the world, with a significant number coming from lung cancer. Lung cancer is caused by a combination of risk factors, primarily environmental agents and genetics. Environmental agents account for the highest percentage of lung cancer cases, with the exposure to environmental tobacco smoke (ETS), either directly or indirectly, being the primary aetiologic factor causing lung cancer. Other than tobacco smoking, the exposure to cooking oil fumes is another lung cancer environmental risk factor. Exposure to oil fumes is the primary environmental factor responsible for lung cancer among the non-smokers. Other than tobacco smoking and the exposure to cooking oil fumes, there is adequate evidence regarding the role of genetic factors on the etiology of lung cancer. Recent studies have identified common genetic variation 15q25.1, mEH exon 3(TYR^113 Hist), MnSOD (Val^16Ala), and exon 4 (Hist ^139Arg) associated with the vulnerability of lung cancer. This review evaluates the current literature on the cases of the development of lung cancer from the influence of genetic and environmental risk factors. Whereas genetic risk factors account for a minimal percentage of lung cancer cases, the environmental risk factors dominate most of the cases of lung cancer deaths. The review establishes that albeit genetic variations contribute to a significant part of lung cancer etiology, tobacco smoking remains the number one risk factor of the deaths associated with lung cancer.
Keywords: Cancer, lung cancer, environmental tobacco smoke, etiology.
Environmental and Genetic Factors on Lung Cancer
In the modern era, cancer assumes a leading position in the number of deaths in most countries. Lung cancer is a chronic disease characterized by uncontrolled cell growth in the lung tissues. It has hitherto contributed to a massive number of deaths in the past couple of decades. Lung cancer develops in an individual depending on their genetic susceptibility and the influence of environmental factors. Cigarette smoking is the single biggest risk factor for the cause of lung cancer (Ji et al., 2014). For the non-smokers, the exposure to cooking oil fumes is the leading environmental factor for the cause of lung cancer. Other external factors include the exposure to second-hand smoking, exposure to occupational carcinogens, and indoor coal burning (Pallis & Syrigos, 2013). This group of individuals may also suffer from the impact of lung cancer due to the direct exposure to tobacco smoke from active smokers. However, cigarette smoking alone does not substantially demonstrate the epidemiologic attributes of lung cancer (Yin et al., 2015). Genetic factors thus chip in to explain the prevalence of lung cancer among nonsmoking individuals. Besides, gene-environment interaction forms a critical part of the development of lung cancer among different individuals. The interaction of genetic factors and environmental factors can either increase or lower the susceptibility to lung cancer among individuals. For instance, the interaction between the risk genotypes of microRNAs (miRNAs) SNPs and cooking oil fumes increases the risk levels of lung cancer (Yin et al., 2015). The interaction between cigarette smoking and CHRNA5 rs3841324 genotypes also increases the susceptibility to human lung cancer (Ji et al., 2014).
Death incidences related to lung cancer are prevalent in China and the United States. In China, the lung cancer associated deaths in the urban areas account to the highest number among malignant tumors. This is a proportion of the total 5 million deaths contributed by cigarette smoking across the world. Cigarette smoking contributes to 31 percent and 6 percent of the total cancer deaths among men and women respectively (Ji et al., 2014). In the United States, a similar trend of lung cancer can be noticed, with the chronic disease being the second most diagnosed type of cancer in the country. Here, the incidence of lung cancer is characterized by racial disparities, with black men having almost twice the incidences of white men (Kim, 2016). Though smoking accounts for the largest number of lung cancer deaths, approximately 15 percent of male cancer patients do not smoke tobacco (Yin et al., 2015). Among the female patients of lung cancer, 53 percent of them are non-smokers. Genetic variations and other environmental factors have, therefore, been implicated in the etiology of the chronic disease.
Different individuals may show varying levels of the susceptibility to lung cancer despite the exposure to the same environmental factors (Yin et al., 2015). The difference in risk levels can be attributed to the view that genetic susceptibility alters the impact of environmental exposures on individuals. The results of different molecular epidemiologic studies show that, other than smoking, lung carcinogenesis is as well caused by gene-gene interactions (Ji et al., 2014; Yin et al., 2015). For instance, microRNAs assume a significant role in the pathogenesis of lung cancer in different individuals (Esquela-Kerscher & Slack, 2006; Yin et al, 2015). Ji and colleagues (2014) as well assert that the chromosome 15q25.1 is an essential susceptibility region for human lung cancer. The role of genetic polymorphisms in modifying the susceptibility of lung cancer among individuals is also analyzed by Ashour, Fathy, Hamed, Youssif, and Fawzy (2013). They argue that the polymorphism of exon 3 and exon 4 often increases the susceptibility of human lung cancer. Other factors associated with increasing the susceptibility of lung cancer include hormonal or dietary factors and having a relative suffering from lung cancer (Osann, 1991; Pallis & Syrigos, 2013). Lung cancer can develop because of a person’s genetic susceptibility and