Objective: We aimed to compare the safety and efficacy of pectoral nerve block (Pecs) I and II with control or other techniques used during breast cancer surgeries such as local anesthesia, paravertebral block, and erector spinae plane block (ESPB). Methods:We searched 4 search engines (PubMed, Cochrane Library, Scopus, and Web of Science) for relevant trials, then extracted the data and combined them under random-effect model using Review Manager Software. Results:We found 47 studies, 37 of them were included in our metaanalysis. Regarding intraoperative opioid consumption, compared with control, a significant reduction was detected in Pecs II (standardized mean difference [SMD] = −1.75, 95% confidence interval [CI] [−2.66, −0.85], P = 0.0001) and Pecs I combined with serratus plane block (SMD = −0.90, 95% CI [−1.37, −0.44], P = 0.0002). Postoperative opioid consumption was significantly lowered in Pecs II (SMD = −2.28, 95% CI [−3.10, −1.46], P < 0.00001) compared with control and Pecs II compared with ESPB (SMD = −1.75, 95% CI [−2.53, −0.98], P < 0.00001). Furthermore, addition of dexmedetomidine to Pecs II significantly reduced postoperative opioid consumption compared with Pecs II alone (SMD = −1.33, 95% CI [−2.28, −0.38], P = 0.006). Conclusion:Pecs block is a safe and effective analgesic procedure during breast cancer surgeries. It shows lower intra and postoperative opioid consumption than ESPB, and reduces pain compared with control, paravertebral block, and local anesthesia, with better effect when combined with dexmedetomidine.

Sentinel lymph node (SLN) sampling is important for evaluating the nodal stage of breast cancer when the axillary nodes are clinically free of metastasis. The intraoperative frozen section (IFS) of SLN is used for lymph node assessment. This meta-analysis aims to provide evidence about the diagnostic accuracy and the applicability of IFS of SLN in breast cancer patients. Data were collected by searching PubMed, Cochrane, Scopus, and Web of Science electronic databases for trials matching our eligibility criteria. The statistical analysis included the sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and pooled studies’ diagnostic odds ratio outcomes. The analyses were conducted using the Open Meta-analyst software. This meta-analysis pooled the results of 110 studies. The overall sensitivity of IFS for SLN metastasis was 74.7%; 95% CI [72.0, 77.2], P < 0.001. It was 31.4% 95% CI [25.2, 38.3], P < 0.001 for the micro-metastasis, and 90.2%; 95% CI [86.5, 93.0], P < 0.001 for the macro-metastasis. The overall specificity was 99.4%; 95% CI [99.2, 99.6], P < 0.001. The overall positive likelihood ratio was 121.4; 95% CI [87.9, 167.6], P < 0.001, and the overall negative likelihood ratio was 0.226; 95% CI [0.186, 0.274], P < 0.001. The overall diagnostic odds ratio of IFS for diagnosing SLN metastasis was 569.5; 95% CI [404.2, 802.4], P < 0.001. The intraoperative frozen section of SLN has good sensitivity for diagnosing breast cancer macro-metastasis. However, the sensitivity is low for micro-metastasis. The specificity is very satisfactory.