PTGDR and neoplasm: Altogether, in head and neck tumors, the exosome's content released by tumor cells, such as proteins (PD-L1, CMTM6, RNF126), and RNA (miR-29a-3p, lncRNA UCA1, LncRNA TP73-AS1), can induce M2 polarization of macrophages by activating the SOCS1/STAT6, ERK1/2, and PI3K/AKT pathways, which promotes immunosuppression, proliferation, migration, invasion, and other malignant progressions of the tumor.