CD226 and neoplasm: NK cells are recruited and localized in the stroma of the tumor rather than in the tumor nest. NK cells exhibited an altered phenotype with down-regulated NKp30, NKp80, CD16, NKG2D, and DNAM-1 while NKp44 and CD69 were over-expressed. Functional studies showed that tumor infiltrating NK cells had impaired cytotoxic functions compared to blood NK cells. Prognostic study in this cohort showed that the presence of NK cells is not associated with clinical outcome at early stages of the disease