In the TCGA colon adenocarcinoma dataset, CTSS expression was significantly negatively correlated with tumor purity (Rho = − 0.172, P = 0.0005) and significantly positively correlated with regulatory T-cells (Rho = 0.45, P = 4.13 × 10−15) and M2 macrophages (Rho = 0.426, P = 1.41 × 10−13; Supplementary Fig. 2A and B). Here, CTSS is linked to neoplasm.