In detail, higher levels of ACP5 (odds ratio, OR = 0.76, 95%CI: 0.67–0.86, p = 1.97 × 10−5), CPB2 (OR = 0.90, 95%CI: 0.86–0.95, p = 5.29 × 10−5), GSTM3 (OR = 0.45, 95%CI: 0.33–0.63, p = 1.86 × 10−6), SHMT1 (OR = 0.74, 95%CI: 0.64–0.86, p = 5.95 × 10−5), CTSB (OR = 0.79, 95%CI: 0.71–0.88, p = 3.07 × 10−5) and NTNG1 (OR = 0.81, 95%CI: 0.74–0.90, p = 4.60 × 10−5) decreased the risk of SCLC, while the elevated level of FAM171B (OR = 1.40, 95%CI: 1.21–1.62, p = 1.97 × 10−5) increased the risk of SCLC. This evidence concerns the gene CTSB and small cell lung carcinoma.