Their high frequency among CD4+ T cells in tumor-infiltrating lymphocytes or a high ratio of FOXP3+ Treg cells to CD8+ T cells is associated with worse prognosis, especially in patients with breast (Bates et al. 2006), gastric (Sasada et al. 2003), and ovarian cancer (Sato et al. 2005). Here, CD4 is linked to neoplasm.