ID4 and neoplasm: Interestingly, we observed that high ID4 expression was strongly associated with low probability of DMFS (n = 232) and OS (n = 241), specifically in the group of tumours characterised by high expression of CD68 (and therefore highly infiltrated by macrophages) (Fig. 1c and Additional file 4: Table S2), whereas no association of ID4 with survival was present in the low-CD68 group (Fig. 1d and Additional file 4: Table S2).