Although lung cancer is largely caused by tobacco smoking, inherited genetic factors play a role in its etiology. Genome-wide association studies in Europeans have only robustly demonstrated 3 polymorphic variations that influence the risk of lung cancer. Tumor heterogeneity may have hampered the detection of association signal when all lung cancer subtypes were analyzed together. In a genome-wide association study of 5,355 European ever-smoker lung cancer patients and 4,344 smoking control subjects, we conducted a pathway-based analysis in lung cancer histologic subtypes with 19,082 single-nucleotide polymorphisms mapping to 917 genes in the HuGE-defined "inflammation" pathway. We identified a susceptibility locus for squamous cell lung carcinoma at 12p13.33 (RAD52, rs6489769) and replicated the association in 3 independent studies totaling 3,359 squamous cell lung carcinoma cases and 9,100 controls (OR = 1.20, Pcombined = 2.3 × 10-8). SIGNIFICA NCE: The combination of pathway-based approaches and information on disease-specific subtypes can improve the identification of cancer susceptibility loci in heterogeneous diseases.
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