Impact of Regional Anesthesia on Recurrence, Metastasis, and Immune Response in Breast Cancer Surgery A Systematic Review of the Literature

Background and Objectives: The perioperative period is critical in the long-term prognosis of breast cancer patients. The use of regional anesthesia, such as paravertebral block (PVB), could be associated with improvements in long-term survival after breast cancer surgery by modulating the inflammatory and immune response associated with the surgical trauma, reducing opioid and general anesthetic consumption, and promoting cancer cells death by a direct effect of local anesthetics. Methods: A systematic literature search was conducted for studies of patients who received PVB for breast cancer surgery. The Jadad score and Ottawa-Newcastle scale were used to assess the methodological quality of randomized controlled trial and observational retrospective studies, respectively. Only high-quality studies were considered for meta-analysis. The selected studies were divided into 3 groups to determine the impact of PVB on (a) recurrence and survival, (b) humoral response, and (c) cellular immune response. Results: We identified 467 relevant studies; 121 of them underwent title and abstract review, 107 were excluded, and 15 studies were selected for full text reading and quality assessment. A meta-analysis was not conducted because of low-quality studies and lack of uniformdefinition among primary outcomes. Thus, a systematic review of the current evidence was performed. Conclusions: Our study indicates that there are no data to support or refute the use of PVB for reduction of cancer recurrence or improvement in cancer-related survival. However, PVB use is associated with lower levels of inflammation and a better immune response in comparison with general anesthesia and opioid-based analgesia.