In the subgroup analyses, SOD3, CBX7, and RORC genes were associated with susceptibility of SCLC in current smokers, while the ABHD14A gene was associated with susceptibility in former smokers; MPHOSPH9 and NDUFV1 genes were strongly associated with SCLC risk in both current and former smokers; and LGALS and PLD4 genes showed a high risk to the development of SCLC but independent of smoking status. This evidence concerns the gene PLD4 and small cell lung carcinoma.