Background::Whether regional anesthesia may help to prevent disease recurrence in cancer patients is still controversial. The stage of cancer at the time of diagnosis is a key factor that defines prognosis and is one of the most important sources of heterogeneity for the treatment effect. We sought to update existing systematic reviews and clarify the effect of regional anesthesia on cancer recurrence in late-stage cancer patients.Methods::Medline, Embase, and Cochrane Library were searched from inception to September 2020 to identify randomized controlled trials (RCTs) and cohort studies that assessed the effect of regional anesthesia on cancer recurrence and overall survival (OS) compared with general anesthesia. Late-stage cancer patients were primarily assessed according to the American Joint Committee on Cancer Cancer Staging Manual (eighth edition), and the combined hazard ratio (HR) from random-effects models was used to evaluate the effect of regional anesthesia.Results::A total of three RCTs and 34 cohort studies (including 64,691 patients) were identified through the literature search for inclusion in the analysis. The risk of bias was low in the RCTs and was moderate in the observational studies. The pooled HR for recurrence-free survival (RFS) or OS did not favor regional anesthesia when data from RCTs in patients with late-stage cancer were combined (RFS, HR= 1.12, 95% confidence interval [CI]: 0.58-2.18, n P = 0.729, n I2 = 76%; OS, HR= 0.86, 95% CI: 0.63-1.18, n P = 0.345, n I2 = 48%). Findings from observational studies showed that regional anesthesia may help to prevent disease recurrence (HR = 0.87, 95% CI: 0.78-0.96, n P = 0.008, n I2 = 71%) and improve OS (HR = 0.88, 95% CI: 0.79-0.98, n P = 0.022, n I2 = 79%).n Conclusions::RCTs reveal that OS and RFS were similar between regional and general anesthesia in late-stage cancers. The selection of anesthetic methods should still be based on clinical evaluation, and changes to current practice need more support from large, well-powered, and well-designed studies.“,”Background::Whether regional anesthesia may help to prevent disease recurrence in cancer patients is still controversial. The stage of cancer at the time of diagnosis is a key factor that defines prognosis and is one of the most important sources of heterogeneity for the treatment effect. We sought to update existing systematic reviews and clarify the effect of regional anesthesia on cancer recurrence in late-stage cancer patients.Methods::Medline, Embase, and Cochrane Library were searched from inception to September 2020 to identify randomized controlled trials (RCTs) and cohort studies that assessed the effect of regional anesthesia on cancer recurrence and overall survival (OS) compared with general anesthesia. Late-stage cancer patients were primarily assessed according to the American Joint Committee on Cancer Cancer Staging Manual (eighth edition), and the combined hazard ratio (HR) from random-effects models was used to evaluate the effect of regional anesthesia.Results::A total of three RCTs and 34 cohort studies (including 64,691 patients) were identified through the literature search for inclusion in the analysis. The risk of bias was low in the RCTs and was moderate in the observational studies. The pooled HR for recurrence-free survival (RFS) or OS did not favor regional anesthesia when data from RCTs in patients with late-stage cancer were combined (RFS, HR= 1.12, 95% confidence interval [CI]: 0.58-2.18, n P = 0.729, n I2 = 76%; OS, HR= 0.86, 95% CI: 0.63-1.18, n P = 0.345, n I2 = 48%). Findings from observational studies showed that regional anesthesia may help to prevent disease recurrence (HR = 0.87, 95% CI: 0.78-0.96, n P = 0.008, n I2 = 71%) and improve OS (HR = 0.88, 95% CI: 0.79-0.98, n P = 0.022, n I2 = 79%).n Conclusions::RCTs reveal that OS and RFS were similar between regional and general anesthesia in late-stage cancers. The selection of anesthetic methods should still be based on clinical evaluation, and changes to current practice need more support from large, well-powered, and well-designed studies.