IDO1 and neoplasm: H1 stage (p = 0.020), metastatic grade A (p = 0.007), low nomogram score (p = 0.020), differentiation in the primary site (p<0.001) (Fig 3C), shallow tumor invasion in the primary site (p = 0.040), immune molecule expression in CRLM (PD-1: p = 0.023, PD-L1: p = 0.007, IDO: p = 0.007), and TAMs and mTAMs in CRLM were identified as significant prognostic factors for better OS (TAMs: p = 0.005; mTAMs: p = 0.031).