Research PAH–DNA Adducts, Cigarette Smoking, GST Polymorphisms, and Breast Cancer Risk Kathleen M. McCarty,1,2 Regina M. Santella,3 Susan E. Steck,4 Rebecca J. Cleveland,1 Jiyoung Ahn,5 Christine B. Ambrosone,6 Kari North,1 Sharon K. Sagiv,1 Sybil M. Eng,7 Susan L. Teitelbaum,8 Alfred I. Neugut,9,10 and Marilie D. Gammon 1 1Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; 2Department of Epidemiology and Public Health, Division of Environmental Health Sciences, School of Medicine, Yale University, New Haven, Connecticut, USA; 3Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York, USA; 4Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia, South Carolina, USA; 5Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland, USA; 6Department of Cancer Prevention and Control, Roswell Park Cancer Institute, Buffalo, New York, USA; 7Epidemiologic Resources, Safety Evaluation, and Epidemiology, Pfizer, Inc., New York, New York, USA; 8Department of Community and Preventive Medicine, Mount Sinai School of Medicine, New York, New York, USA; 9Department of Epidemiology, Mailman School of Public Health, and 10Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York, USA Background : Polycyclic aromatic hydrocarbons (PAHs) may increase breast cancer risk, and the association may be modified by inherited differences in deactivation of PAH intermediates by glutathione S-transferases (GSTs). Few breast cancer studies have investigated the joint effects of multiple GSTs and a PAH biomarker. o Bjectiv : We estimated the breast cancer risk associated with multiple polymorphisms in the GST gene (GSTA1, GSTM1, GSTP1, and GSTT1) and the interaction with PAH–DNA adducts and cigarette smoking. Methods : We conducted unconditional logistic regression using data from a population-based sample of women (cases/controls, respectively): GST polymorphisms were genotyped using poly- merase chain reaction and matrix-assisted laser desorption/ionization time-of-flight assays (n = 926 of 916), PAH–DNA adduct blood levels were measured by competitive enzyme-linked immunosor- bent assay (n = 873 of 941), and smoking status was assessed by in-person questionnaires (n = 943 of 973). r sulte c onclusi k ey : Odds ratios for joint effects on breast cancer risk among women with at least three variant alleles were 1.56 [95% confidence interval (CI), 1.13–2.16] for detectable PAH–DNA adducts and 0.93 (95% CI, 0.56–1.56) for no detectable adducts; corresponding odds ratios for three or more variants were 1.18 (95% CI, 0.82–1.69) for ever smokers and 1.44 (95% CI, 0.97–2.14) for never smokers. Neither interaction was statistically significant (p = 0.43 and 0.62, respectively). : We found little statistical evidence that PAHs interacted with GSTT1, GSTM1, GSTP1, and GSTA1 polymorphisms to further increase breast cancer risk. words : breast cancer, GST, Long Island, PAH–DNA adducts, smoking. Environ Health Perspect 117:552–558 (2009). doi:10.1289/ehp.0800119 available via http://dx.doi.org/ [Online 10 December 2008] Polycyclic aromatic hydrocarbons (PAHs) are an environmentally ubiquitous class of com- pounds that are formed during incomplete combustion of organic substances. Several PAHs have been classified as probable human carcinogens (Boffetta et al. 1997; Shimada 2006). In the general population, the major source of exposure is tobacco smoke (Lioy and Greenberg 1990), with diet (grilled/ smoked foods, cereals, and leafy green veg- etables) and exposure to fossil fuel combus- tion by-products contributing to cumulative exposure (Waldman et al. 1991). Although there is strong evidence for the relationship between PAH exposure and lung, skin, and bladder cancer in humans, it is equivocal as to whether PAH exposure is associated with breast cancer (Boffetta et al. 1997; Gammon and Santella 2008; Shimada 2006). PAH–DNA adducts reflect not only PAH exposure but also the body’s ability to metabolize these compounds. The forma- tion of these carcinogen–DNA adducts is 552 recognized as a key event in the initiation of carcinogenesis (Gammon et al. 2004b; Hecht 2003; Wogan et al. 2004). In the Long Island Breast Cancer Study Project (LIBCSP), a large population-based case–control study, blood levels of PAH–DNA adducts were associated with a modest 29–35% elevation in breast cancer risk among women (Gammon et al 2004b). These findings are consistent with previously conducted, smaller hospital-based studies (Li et al. 1996, 2002; Rundle et al. 2000a). Animal studies have provided fur- ther support for the role of PAHs as mam- mary carcinogens (Cavalieri et al. 1991; el-Bayoumy et al. 1995). Although a signifi- cant association between breast cancer risk and detectable PAH–DNA adducts has been noted, a dose–response relationship was not observed in the LIBCSP. Further stratifica- tion by known sources of PAH exposure, such as cigarette smoking or the consumption of PAH-containing foods, did not modify this association (Gammon et al. 2004b). These findings are consistent with those from smaller studies (Hu et al. 2007). The lack of a dose response effect suggests that there may be sub- groups of women who are more genetically susceptible to the carcinogenic effects of PAH exposure on breast tissue. Inherited differences in the metabolism of PAHs, interindividual differences in enzyme expression, and induction may be key determi- nants in individual breast cancer susceptibility (Shimada 2006). Genetic differences in meta- bolic activation and detoxification of PAHs have been shown to affect differences in phe- notypic biomarkers such as urinary metabolites and are hypothesized to influence cancer risk (Brescia et al. 2004; Hatsukami et al. 2006; Hecht et al. 2006; Kuljukka-Rabb et al. 2002; Upadhyaya et al. 2006; Wogan et al. 2004). Further investigation of these genetic differ- ences in the deactivation of PAH metabo- lites may contribute to our understanding of the lack of a dose–response relationship and increased understanding of breast cancer risk. The phase II metabolic super family of GST enzymes is involved in the metabolic activation and deactivation of PAH metabo- lites, and polymorphisms in these genes lead to specific changes in enzyme function and the capacity to metabolize PAH compounds (Hecht 1999). The GSTM1 polymor- phism [GenBank BC036805; National Center for Biotechnology Information (NCBI) 2009a] results in the absence of isoenzyme (mu) Address correspondence to K.M. McCarty, Yale University Epidemiology and Public Health, Environmental Health Sciences Division, 60 College St., Room 442, New Haven, CT 06520-8034 USA. Telephone: (203) 785-2880. Fax: (203) 737-6023. E-mail: kathleen.mccarty@yale.edu This work was supported in part by grants from the National Cancer Institute and the National Institutes of Environmental Health Sciences of the National Institutes of Health (grants CA/S66572, P30ES10126, P30ES009089, 1K07CA102640, 5T32CA 009330, and L30 CA124219-01). The authors declare they have no competing financial interests. Received 21 August 2008; accepted 8 December 2008. ovlume 117 | number 4 | April 2009 • Environmental Health Perspectives