Lung Cancer in Never Smokers: Clinical Epidemiology and Environmental Risk Factors

Abstract

More than 161,000 lung cancer deaths are projected to occur in the U.S. in 2008. Of these, an estimated 10–15% will be caused by factors other than active smoking, corresponding to 16,000–24,000 deaths annually. Thus lung cancer in never smokers would rank among the most common causes of cancer mortality in the U.S. if considered to be a separate category. Slightly more than half of the lung cancers caused by factors other than active smoking occur in never smokers. As summarized in the accompanying article, lung cancers that occur in never smokers differ from those that occur in smokers in their molecular profile and response to targeted therapy. These recent laboratory and clinical observations highlight the importance of defining the genetic and environmental factors responsible for the development of lung cancer in never-smokers. This article summarizes available data on the clinical epidemiology of lung cancer in never smokers, and the several environmental risk factors that population-based research has implicated in the etiology of these cancers. Primary factors closely tied to lung cancer in never smokers include exposure to known and suspected carcinogens including radon, second-hand tobacco smoke, and other indoor air pollutants. Several other exposures have been implicated. However, a large fraction of lung cancers occurring in never-smokers cannot be definitively associated with established environmental risk factors, highlighting the need for additional epidemiologic research in this area.

Association of Cadmium but not Arsenic Levels in Lung Cancer Tumor Tissue with Smoking, Histopathological Type and Stage

“…Cigarette smoke contains measurable amounts of cadmium, and passive smokers living in the same households as smokers have significantly higher blood cadmium levels (Wysowski et al, 1978). Nonetheless, never smokers have also been lung cancer due to environmental risk factors and carcinogenic effects of metals were seen among non-smokers (Samet et al, 2009). As similar to previous studies, cadmium levels were showed significantly higher in tumor tissue obtained from current smokers in present study.…”

Correlation analysis of lung cancer and urban spatial factor: based on survey in Shanghai

“…External traffic volume, surrounding land uses, presence of green space/ water-body and age of housing present their significance. Non-smoking female patients are increasing recently (59,60). It indicates that the causes of lung cancer in China are more complicated than smoking.…”

Bayesian spatio-temporal modelling of tobacco-related cancer mortality in Switzerland

“…Several recent reviews of lung cancer in people who never smoked have highlighted the importance of other risk factors such as genetic predisposition and various forms of exposure, e.g. environmental tobacco smoke, outdoor air pollution, ionizing radiation as well as occupational exposures to carcinogens (Samet et al, 2009;Torok et al, 2011;Couraud et al, 2012). The second most important cause of lung cancer in Switzerland (but far behind that of tobacco) is exposure to radon, especially in alpine regions and in the Jura.…”