IL31 and metastatic neoplasm: MBC patients’ exosomes had a low concentration of MIP-3 alpha, IL-23, M-CSF, Eotaxin-3, BLC, SDF-1 alpha, IL-2R, MDC, FGF-2, IL-22, and IL-31, suggesting that metastatic disease may be associated with immune suppression related to low exosomal cytokines.