CTSH and squamous cell lung carcinoma: Meta‐analysis of the IVW results from three databases showed a strong association between CTSH and lung adenocarcinoma (OR = 1.06, 95% CI = 1.02–1.10, P < 0.01), while lung squamous cell carcinoma lost significance (OR = 1.04, 95% CI = 1.00–1.08, P = 0.05) (Figure 3C,D).