CD4 and cancer: An increased proportion of Tregs and CTLA4+CD4+ lymphocytes was found in both benign and malignant tumor patients compared to the control group, with the ratio being significantly higher in the malignant tumor group (7.74 ± 1.1 for Tregs and 8.18 ± 1.77 for CTLA4+CD4+ cells in malignant tumors, vs. 4.38 ± 0.56 for Tregs and 3.83 ± 0.56 for CTLA4+CD4+ cells in benign tumors, and 2.34 ± 0.28 for Tregs and 2.22 ± 0.25 for CTLA4+CD4+ cells in controls).