The presence of tumor-specific CD4 and CD8 T cells at the tumor site is in many cases considered a good prognostic factor (21, 22); however studies conducted in different type of cancers over the past decade have shown that, whereas the infiltration by CD8 T cells is generally considered sign of a good prognosis, the ratio CD8 T cells/Tregs has a more critical role as prognostic factor (23). The gene discussed is CD8A; the disease is cancer.