Cathepsin L2 was found to have a promoting effect on skin cancer (odds ratio [OR] = 1.233, 95% confidence interval [CI]: 1.033–1.525, P < .05), while cathepsin F (OR = 1.048, 95% CI: 1.004–1.094, P < .05) and cathepsin O (OR = 1.053, 95% CI: 1.008–1.100, P < .05) were associated with an increased risk of BCC. Here, CTSO is linked to skin cancer.