As shown in Table 2, the expression of IDO1 was significantly increased in all gastric tumors vs. their peritumoral counterpart (×2.2, p < 0.0001), with IDO1 expression being significantly higher in both the intestinal (×3, p = 0.0006) and diffuse (×1.96, p = 0.002) GC subtypes as compared to non- tumoral gastric tissues (Table 2). Here, IDO1 is linked to gastric neoplasm.