Effect of non-invasive brain stimulation on cancer-related pain: evidence from meta-analyses of randomized controlled trials.

Purpose: Cancer-related pain (CRP) is one of the most challenging disorders among cancer survivors. Non-invasive brain stimulation (NIBS) is an emerging technique for alleviating pain. Although there is evidence suggesting that NIBS can alleviate CRP, higher level evidence is still required to further substantiate its efficacy and safety. This study aimed to evaluate the efficacy of NIBS interventions for CRP via a meta-analysis.

Methods: Databases such as MEDLINE, PubMed, Embase, CINAHL, PsycINFO, Cochrane Central Register of Controlled Trials (CENTRAL), ClinicalTrials.gov, China National Knowledge Infrastructure were systematically searched using key terms related to pain, cancer, and NIBS. The primary outcome was pain intensity and the secondary outcome was depression. After extracting and assessing data from the included literature, we performed Meta-analysis using RevMan 5.4.1 software.

Results: The results encompassed 11 randomized controlled trials papers, involving 714 patients. The Meta-analysis findings indicated that NIBS demonstrated a significant reduction in pain intensity scores {SMD -0.72 [95% confidence interval (CI), -1.00 to -0.43], P < 0.00001}. NIBS also had a notable effect on depression [SMD -0.62 (95% CI, -0.93 to -0.31), P = 0.0004]. However, subgroup analysis revealed that one single session of NIBS did not show statistical significance in analgesic effect. Furthermore, no matter targeting the M1 and DLPFC areas, as well as using either rTMS or tDCS, resulted in significant reductions in pain intensity.

Conclusion: NIBS exhibited a promising trend in alleviating CRP and enhancing treatment effectiveness. Nonetheless, due to limitations in the quantity and quality of the included studies, these findings warrant further validation through additional research.