Due to the low number of cases positive for IDO-1 manual assessment in the tumour only, stroma only and whole core was the most optimal method using a (0 = 0%, 1 = 1–33%, 2 = 34–66%, 3 ≥ 66%) scoring system reported for IDO-1 assessment in breast cancer tissue [27]. Here, IDO1 is linked to breast cancer.