In 1998, 80,000 women in the US were diagnosed with lung cancer and incidence rates, particularly of adenocarcinoma, continue to increase among women. Many pieces of evidence suggest that there are gender differences in susceptibility to tobacco carcinogens. Several studies have shown that DNA adducts, p53 mutations, CYP1A1 expression in the lung, and GSTM1 null genotypes are more frequent in females than in males. Reasons for differential susceptibility by gender might be explained by variations in metabolic enzyme functioning or hormonal differences. Some of the same enzymes involved in the metabolism of carcinogens in tobacco smoke are involved in the metabolism of estrogen. The goals of the proposed study are two-fold. First, we will evaluate the role of tobacco smoke and estrogens in determining risk of adenocarcinoma of the lung among women. Secondly, we will evaluate the role of estrogen receptors and c-erbB-2 in lung tumors to further understand the pathways through which estrogen may be acting in the lung.
The specific aims are: 1) To conduct a population-based case-control study of the contribution of tobacco exposure, estrogen use, and reproductive history in determining risk of adenocarcinoma of the lung in women. 716 cases will be identified through the Metropolitan Detroit Cancer Surveillance System of the Karmanos Cancer Institute (a SEER participant). An equal number of controls will be selected through random digit dialing. 2) To determine if genotype at the metabolic enzyme loci CYP1A1, CYP1B1, CYP17, CYP19, GSTM1, GSTP1, COMT, and NQO1 are associated with risk of adenocarcinoma of the lung in women. These enzymes are active in both the metabolism of tobacco smoke carcinogens and the synthesis and metabolism of estrogens. 3) To examine gene-gene and gene-environment interactions, focusing on tobacco and estrogen effects. 4) To determine estrogen receptor status (alpha and beta) and c-erbB-2 levels in the lung tumors of women with adenocarcinoma and evaluate risk associated with tobacco exposure, estrogen use, reproductive history, and genotype at metabolic enzyme loci by tumor characteristics. The proposed study represents a focused approach to defining the contribution of genes and environments in risk of adenocarcinoma of the lung in women. The interview component of the study will provide data about individually measured environmental risk factors. Genotypes have been chosen which impact on biologically effective dose of tobacco carcinogens and estrogens in the lung. The study of tumor characteristics will provide insight into mechanism of action. This large, population-based study should provide clues for important prevention and therapeutic strategies for lung cancer.
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