Fig. 5

The coverage and intensity of IDO+ tumor cells and their association with survival. IDO+ tumor cell coverage (a) was analysed from all samples using 5-level scoring system from 0 to 4. Statistically significant differences between the stages are shown with brackets (Kruskal–Wallistest). *P < 0.05, **P < 0.01, ***P < 0.001. IDO expression intensity (b) was also analysed from malignant tumors that contained more than 1% IDO+ tumor cells of all melanoma cells. IDO expression was classified as weak, moderate or strong. Representative stainings for weak, moderate and strong IDO expression in melanoma cells are represented in e-g, respectively. In survival analyses (c, d) samples were divided into two groups, IDO-negative and IDO-positive tumors, representing tumors that contained less than 1% or more than 1% IDO+ tumor cells of all melanoma cells. IDO-positive tumors was associated with poor recurrence-free survival (RFS) in the group of all samples (pT1, pT4, LNM) (c) and in the group of primary melanomas only (d) (P-values 0.019 and 0.036, respectively)