Our results suggest that in lung adenocarcinoma, this finding may be associated with the mechanisms of carcinogens different than those activated by CYP2A6. Ariyoshi et al. demonstrated that the CYP2A6 whole-gene deletion was not found in male smokers among Japanese patients with squamous cell carcinoma (0 of 105)14, which is consistent with our results. Here, CYP2A6 is linked to lung adenocarcinoma.