CD4 and ovarian cancer: CD4+CD25+Tregs can be detected in peripheral blood of patients with gastric cancer, lung cancer, ovarian cancer, liver cancer, pancreatic cancer and breast cancer, local tumors, invasive lymph nodes, and drainage lymph nodes, and the number of CD4+CD25+Treg cells is negatively correlated with the disease course and the prognosis; the higher the number of Tregs, the worse the prognosis 13.