Genetic polymorphisms and environmental risk of lung cancer: a review.

Lung cancer results from man-made and natural environmental exposures acting in concert with both genetic and acquired characteristics. Chronic inhalation of cigarette smoke is a major risk factor, and environmental tobacco exposure can cause lung cancer in life-long neversmokers. Air pollution, indoor-radon exposure, occupational exposures, dietary, physical activity, and reproductive history have been identified as independent or contributing risk factors for lung cancer. Because only a small portion of smokers develops the disease, genetic susceptibility can contribute to the risk. Developments in molecular biology have led to the discovery of biological markers that increase predisposition to lung carcinogenesis. Therefore, the high-risk genotype of an individual can be determined easily. Because of the great number of carcinogen-activating and -detoxifying enzymes, the variation in their expression, the complexity of exposures to tobacco carcinogens, and the existence of multiple alleles at loci of those enzymes results in differential susceptibilities of individuals. As lung cancer is a multifactorial disease, an improved understanding of the interplay of environmental and genetic polymorphisms at multiple loci can help identify individuals who are at increased risk for lung cancer. Hopefully, in the future we will be able to screen for lung cancer susceptibility by using specific biomarkers.