AIM:To investigate the effect of perioperative restricted fluid therapy on circulating CD4+/CD8+T lymphocyte ratio,percentage of regulatory T cells(Treg)and postoperative complications in patients with colorectal cancer.METHODS:A total of 185 patients met the inclusion criteria and were included in the randomized clinical trial.These patients were divided into two groups according to receipt of either perioperative standard(S,n=89)or restricted(R,n=96)fluid therapy.Clinical data of these patients were collected in this prospective study.Perioperative complications and cellular immunity changes(CD4+/CD8+and Treg)were analyzed comparatively between the two groups.RESULTS:Both during surgery and on postoperativedays,the total volumes of fluids administered in the R group were significantly lower than those in the S group(1620±430 mL vs 3110±840 mL;2090±360mL vs 2750±570 mL;1750±260 mL vs 2740±490mL;1620±310 mL vs 2520±300 mL;P<0.05).Decreased ratios of circulating CD4+/CD8+T lymphocytes(1.47±0.28 vs 2.13±0.26;1.39±0.32 vs 2.21±0.24;P<0.05)and Treg percentage values(2.79±1.24vs 4.26±1.04;2.46±0.98 vs 4.30±1.12;P<0.05)were observed after surgery in both groups.However,in the R group,these values restored more quickly starting from postoperative day 2(1.44±0.24 vs 1.34±0.27;2.93±1.08 vs 2.52±0.96;P<0.05).The proportion of patients with complications was significantly lower in the restricted group(36 of 89 vs 59 of 96,P<0.01).CONCLUSION:Perioperative restricted intravenous fluid regimen leads to a low postoperative complication rate and better cellular immunity preservation in patients with colorectal cancer. AIM: To investigate the effect of perioperative restricted fluid therapy on circulating CD4 + / CD8 + T lymphocyte ratio, percentage of regulatory T cells (Treg) and postoperative complications in patients with colorectal cancer. METHODS: A total of 185 patients with the inclusion criteria and were included in the randomized clinical trial. These patients were divided into two groups according to receipt of either perioperative standard (S, n = 89) or restricted (R, n = 96) fluid therapy. Clinical data of these patients were collected in this prospective study. Perioperative complications and cellular immunity changes (CD4 + / CD8 + and Treg) were analyzed comparatively between the two groups .RESULTS: Both during surgery and on postoperative days, the total volumes of fluids administered in the R group were significantly lower than those in the S group (1620 ± 430 mL vs 3110 ± 840 mL; 2090 ± 360 mL vs 2750 ± 570 mL; 1750 ± 260 mL vs 2740 ± 490 mL; 1620 ± 310 mL vs 2520 ± 300 mL; P <0.05) circulating CD4 + / CD8 + T lymph The percentages of octetes (1.47 ± 0.28 vs 2.13 ± 0.26; 1.39 ± 0.32 vs 2.21 ± 0.24; P <0.05) and Treg percentage values ​​(2.79 ± 1.24 vs 4.26 ± 1.04; 2.46 ± 0.98 vs 4.30 ± 1.12; P <0.05) surgery in both groups. Despite, in the R group, these values ​​restored more quickly starting from postoperative day 2 (1.44 ± 0.24 vs 1.34 ± 0.27; 2.93 ± 1.08 vs 2.52 ± 0.96; P <0.05). proportion of patients with complications was significantly lower in the restricted group (36 of 89 vs 59 of 96, P <0.01) .CONCLUSION: Perioperative restricted intravenous fluid regimen leads to a low postoperative complication rate and better cellular immunity preservation in patients with colorectal cancer.