Paravertebral Block versus Erector Spinae Plane Block for Prevention of Chronic Pain after Breast Cancer Surgery

Background: Chronic postsurgical pain is frequent after breast cancer surgery, and regional analgesia has been proposed to limit its development. Thoracic paravertebral block is established, and erector spinae plane block is more superficial. In this study we aimed to compare their effectiveness in preventing pain persisting for at least three months after breast cancer surgery. Methods: PubMed/MEDLINE, Scopus, Web of Science Core Collection, and CENTRAL were searched from inception through August 2026. Randomized trials of adults undergoing oncological breast surgery were eligible when either block was evaluated and pain was measured at three months or later. Outcomes were chronic pain incidence, neuropathic features, severity, functional interference, acute analgesia, and adverse events. Risk of bias was assessed with RoB 2, and certainty through GRADE domains. Heterogeneous definitions and comparators supported narrative synthesis. Results: Twelve randomized trials met eligibility criteria. Two compared the blocks, one reported no chronic pain in either group at six months, while another found similar neuropathic-pain scores. Paravertebral trials produced conflicting results, from meaningful reductions to no benefit in the largest placebo-controlled study. Erector spinae trials improved acute analgesia, although the largest placebo-controlled trial found no significant chronic-pain reduction at three or six months. Conclusion: Paravertebral block has a larger, inconsistent chronic-pain evidence base; evidence for erector spinae block remains limited and negative.