These results indicated that CAFs, which are one of the major components of stroma in peritoneal metastasis, interfered with the accumulation of CD8+ lymphocytes by secreting several cytokines or chemokines such as vascular endothelial growth factor (VEGF) and transforming growth factor‐β (TGF‐β), which act as immunosuppressors in the tumor microenvironment. The gene discussed is TGFB1; the disease is neoplasm.