In an in vitro experiment, the results showed that IFN-γ and TNF-α could enhance the expression of IDO and IL-6 in prostate cancer cells at the gene and protein levels, and the data showed that the expression of IDO and IL-6 genes was higher in prostate cancer than in prostate hyperplasia, and that their expression was highly significantly correlated with the expression of IFN-γ and TNF-α genes [74]. Here, IDO1 is linked to benign prostatic hyperplasia.