Background:
Laparoscopic surgery (LS) and open surgery (OS) are the main surgical treatment options for colorectal cancer (CRC), which might differ in their impact on host immunity so indispensable for anti-infectious and antitumor defence.

Methods:
Included in this systematic review and meta-analysis were randomized controlled trials (RCTs) measuring parameters of humoral immunity up to eight days after LS compared to OS in adult patients with CRC of any stage. MEDLINE, Embase, Web of Science (SCI-EXPANDED), Cochrane Library, Google Scholar, ClinicalTrials.gov and ICTRP were systematically searched. Risk of bias (RoB) was assessed using the Cochrane RoB2 tool. Random-effects meta-analysis of mean differences (MD) was performed. Methods were prospectively registered in PROSPERO (CRD42021264324).

Result:
Twenty RCTs with 1,131 participants were included. RoB was rated low in five, of some concerns in 13, and high in two studies. Quantitative synthesis found concentrations of parameters to be significantly lower after LS for IL-6 and CRP at 3-9h (CRP MD -1.67 mg/dl 95% CI -3.25, -0.08 p=0.04, IL-6 -86.71 pg/ml -125.05, -48.37 p{}0.00001), at post-operative day (POD) 1 (CRP -3.68 mg/dl -5.05, -2.32 p{}0.00001, IL-6 -26.88 pg/ml -31.27, -22.50 p{}0.00001) and at POD 2 (IL-6 -11.47 pg/ml -16.32, -6.63 p{}0.00001). IL-8, TNF{a} and VEGF also showed lower concentrations after LS at 0-2h (IL-8), 3-9h (IL-8, TNF{a}) and POD 1 (IL-8, VEGF). No meta-analysis yielded results favouring the OS group.

Discussion:
The increase in postoperative concentrations of several proinflammatory parameters was significantly less pronounced after LS in the analyses, especially in the early postoperative period up to POD1. The main limitations of the included RCTs were small sample sizes and a heterogenous choice of measuring timepoints.

Conclusion:
The summarized evidence favours the laparoscopic approach over the open approach in regard to a milder postoperative proinflammatory reaction, although further research is desirable.

Disclosure Statement: The authors declare no conflict of interest.