Intriguingly, the trend that IDO1 was associated with poor OS in patients with colon cancer was shown (HR = 1.621, 95% CI: 0.801–3.281, P = 0.101) (Figure 1F) based on the secondary cut-off value of IDO1 level (represented by a red arrow in Figure 1D). Here, IDO1 is linked to colonic neoplasm.