Moreover, multivariable MR analysis confirmed a significant direct effect of cathepsin H on lung cancer risk among individuals with a smoking history (p = 1.777 × 10–5, OR = 1.092, 95% CI = 1.049–1.137) (Fig. 4), with the results of the MR-Egger intercept analysis again indicating no existence of directional horizontal pleiotropy (Supplementary Data 1). This evidence concerns the gene CTSH and lung carcinoma.