IDO1 and colorectal cancer: We demonstrated that CEA level (ng/mL) (>5 vs. ≤5) (p = 0.007; HR = 2.538; 95% CI: 1.291–5.000) and IDO-1/COX2 (Group IV vs. Group I/II/III) (p = 0.013; HR = 2.347; 95% CI: 1.197–4.608) were significantly correlated with PFS in patients with liver oligometastases of colorectal cancer (Table 2).