HMOX1 and lung adenocarcinoma: Although there is evidence of gender bias in the distribution of this allelic variant in HMOX1 with respect to development of lung adenocarcinoma in Japanese smokers [34], there was no difference in the allele lengths between males and females in any of the groups from our study, so we do not think that the differences in the proportions of males and females between the groups had an impact on our observations.