POSTN and neoplasm: POSTN‐high tumors (as assessed by IHC) were associated with higher tumor cell‐to‐stroma ratio, as evidenced by high relative Pan‐CK immunostaining (p = 0.011) (supplementary material, Figure S2A), and low abundance of collagen, specifically for ‘pure’ POSTN‐high tumors (POSTN high alone, i.e. expressing POSTN but not PDPN or MYH11 by IHC) (POSTN‐high alone versus POSTN‐low, Pan‐CK, p = 0.017, Figure 3C, and Picro‐Sirius Red staining, p = 0.017, Figure 3D).