Efficacy of pectoral nerve block type-2 (Pecs II block) versus serratus plane block for postoperative analgesia in breast cancer surgery: a retrospective study

Thoracic wall nerve blocks reduce postoperative acute pain after breast cancer surgery (BCS); however, their short-term effects and the most effective technique remain unclear. To compare the effects of pectoral nerve block type-2 (Pecs II block) and serratus plane block for postoperative short-term analgesia, we retrospectively reviewed 43 BCS patients who underwent Pecs II block (n=22) or serratus plane block (n=21). The primary outcome was the proportion of patients with no complaints of pain 2 months post-BCS. The odds ratio (OR) was assessed, adjusting for axillary lymph node dissection. The secondary outcomes were pain severity 24 hours and 2 months post-operation using the numerical rating scale score, and morphine consumption within 24 hours. The proportion of patients without pain 2 months post-BCS was significantly less with Pecs II block than in patients with serratus plane block (55% vs. 19%, adjusted OR, 5.04; 95% confidence interval, 1.26-20.07; P=0.02): the median [interquartile range] score for pain 2 months post-operation was also significantly lower with Pecs II block (Pecs II block 0.5 [0-1] vs. serratus plane block 1 [1-2]); P=0.03). Regarding post-BCS acute analgesia, the median [interquartile range] postoperative 24-hour pain score was 2 [1-3] and 3 [1.5-3.5], and the median morphine consumption within 24 hours was 1.5 [0.75-5.5] and 3 [1.5-10] mg in Pecs 11 block and serratus plane block (P=0.47 and P=0.11), respectively. This study suggests that Pecs II block prevents short-term post-BCS pain better than seams plane block. However, further studies are needed in order to support this finding.