IDO1 and melanoma: In univariate survival analyses, IDO-positive tumors were associated with poor recurrence-free survival (RFS), both in analyses conducted in all groups (pT1, pT4, LNMs) (Fig. 5C) and primary melanomas only (Fig. 5D) (p-values 0.019 and 0.036, and number on events 36 and 15, respectively).