The role of thoracic paravertebral block (PVB) in preventing chronic postsurgical pain (CPSP) after breast cancer surgery (BCS) has gained interest, but existing evidence is conflicting, and its methodological quality is unclear. This meta-analysis evaluates efficacy of PVB, compared with Control group, in preventing CPSP after BCS, in light of the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) recommendations. Electronic databases were searched for randomized trials comparing PVB with Control group for CPSP prevention after BCS. Eligible trials were assessed for adherence to IMMPACT recommendations. The primary outcomes were CPSP at 3 and 6 months, whereas secondary outcomes were PVB-related complications. Data were pooled and analyzed using random-effects modelling. Trial sequential analysis was used to evaluate evidence conclusiveness. Data from 9 studies (604 patients) were analyzed. The median (range) of IMMPACT recommendations met in these trials was 9 (5, 15) of 21. Paravertebral block was not different from Control group in preventing CPSP at 3 months, but was protective at 6 months, with relative risk reduction (95% confidence interval) of 54% (0.24-0.88) (P = 0.02). Meta-regression suggested that the relative risk of CPSP was lower when single-injection (R = 1.00, P < 0.001) and multilevel (R = 0.71, P = 0.01) PVB were used. Trial sequential analysis revealed that 6-month analysis was underpowered by at least 312 patients. Evidence quality was moderate according to the GRADE system. Evidence suggests that multilevel single-injection PVB may be protective against CPSP at 6 months after BCS, but methodological limitations are present. Larger trials observing IMMPACT recommendations are needed to confirm this treatment effect and its magnitude.
Chronic pain after breast surgery is quite rare but, in effect, it represents a main topic in consideration of the difficulty to diagnose it and moreover to treat the symptom. This is a very useful paper.
As a general surgeon with oncological interest, I find this an important paper as it provides useful guidelines and evaluates them regarding the management of breast cancer pain.
As an Oncologist, I believe more prolongued follow-up times for these women is key in assessing the pain scores as well as functional impairment. As such, I would have liked to have seen evaluation of time points further than 6 months after surgery. The study diversity as well as the fact that the meta-analysis was still underpowered for the most interesting time-point (6 months) makes this article an interesting, but not practice-changing one.
Post surgical breast cancer pain has many origins, the least being large and deep scar tissue that impacts on the shoulder neck function, resulting in referred pain. Outcomes to single interventions can not be expected to solve pain of complex and varying origins.