In pancreatic cancer, tumor-associated macrophages are a marker of poor prognosis and tumor cells interact with macrophages via IL-13 to induce their differentiation into the M2 phenotype, which not only promotes tumor growth, metastasis and angiogenesis [98,99], but also recruits regulatory T lymphocytes (Tregs) and inhibits the cytotoxic effects of effector T lymphocytes on tumors [100]. This evidence concerns the gene IL13 and neoplasm.