The association with SNPs that we found to be protective for heavy smoking with lung cancer was only investigated in one of the GWASs for lung cancer. Hung et al. (11) found three of these SNPs (rs637137, rs578776, and rs3743078) to be unrelated to lung cancer risk. The association of these SNPs with heavy smoking in our study was unaffected by the removal of individuals with lung cancer and no direct association with lung cancer risk was observed. Thus, comparison of these risk and protective SNPs in lung cancer studies may be helpful in defining whether associations with the cancer are direct or are through an association with smoking behavior.
