Consistent with the aforementioned findings, Wang et al. showed that intratumoral neutrophils infiltration was an independent prognostic factor for poor survival for HCC patients and that the percentage of intratumoral neutrophils infiltration was much higher in high indole-amine-2,3-dioxygenase (IDO) expression group than that in low IDO expression group, indicating that IDO might play a role in the recruitment of neutrophils [59]. The gene discussed is IDO1; the disease is hepatocellular carcinoma.