IDO1 and colorectal cancer: We observed that CEA level (ng/mL) (>5 vs. ≤5) (p = 0.050; HR = 2.137; 95% CI: 1.001–4.566) and IDO-1/COX2 (Group IV vs. Group I/II/III) (p = 0.002; HR = 2.315; 95% CI: 1.052–5.102) were significantly correlated with OS for patients with liver oligometastases of colorectal cancer (Table 2).