The Immunomodulatory Effect of Various Anesthetic Factors and Techniques on Patients Undergoing Breast Cancer Surgery: A Systematic Review and Meta-analyses of RCTs.

Breast cancer is the most common type of cancer among women, while several factors seem to play a role in carcinogenesis. Recent findings suggest that some anesthetic factors and techniques contribute to immune suppression and metastasis, while others have beneficial effects. The aim of this meta-analysis is to identify the overall effects of different anesthetic modalities on the patients' immune system after breast cancer surgery. A systematic search was conducted from February 2026 to March 2026 in PubMed, CENTRAL, and Scopus. Only Randomized controlled trials were included. As primary endpoints were considered CD4+ T cell, CD8+ T cell, and Natural killer (NK) cell counts at 24, 48, and 72 hours after the end of the surgery. As secondary endpoints were considered, Leucocytes, Lymphocytes, Neutrophils, the Neutrophil- to- Lymphocyte ratio (NLR), CD4+/CD8+, IL-2, IL-6, Matrix metalloproteinase-9 at the same time points. Sixteen studies met the inclusion criteria. We concluded in positive effects of the combination of general anesthesia (GA) and regional anesthesia on CD4+ T cells (Standardized mean difference (SMD) 0.35 [0.06; 0.64], I2 38.7%), NK cells (SMD 0.40 [0.05; 0.75], I2 56%), and NLR (SMD -0.42 [-0.64; -0.19], I2 0%) 24 hours after surgery. Also, the comparison between total intravenous anesthesia and inhalational anesthesia revealed a statistically significantly higher total leukocyte count in the inhalational anesthesia group (SMD 0.61 [0.19; 1.03], I2 0%). Combined regional and GA exerts a beneficial effect regarding NK cell counts, CD4+ T cell counts, and NLR (PROSPERO: CRD42024564788).