This may be due to the depletion of T cells under the long-term suffering of tumor, but there are still memory T cells and the main functions of T cells are preserved, such as T cell activation and regulation, antigen processing and presentation, leukocyte mediated immunity, in contrast, exhausted T cell (CD8+Tex) showed downregulation and silencing of most of immunofunctional genes. This evidence concerns the gene CD8A and neoplasm.