Supplementary Material for: Protective Effects of Vitamin E on Chemotherapy-Induced Peripheral Neuropathy: A Meta-Analysis of Randomized Controlled Trials

Introduction: Chemotherapy-induced peripheral neuropathy (CIPN) is a common symptom, but prophylactic measures cannot still be carried out effectively. In addition, the efficacy of vitamin E in preventing peripheral neurotoxicity caused by chemotherapy is inconclusive. Therefore, we collected the relevant randomized controlled trials (RCTs) and performed a meta-analysis to examine whether the vitamin E has a positive effect in CIPN. Methods: We searched PubMed, EMBASE, Cochrane, and other databases in December 2019 for eligible trials. Two reviewers conducted the analysis independently when studies were homogeneous enough. Results: Eight RCTs, involving 488 patients, were identified. Upon pooling these RCTs, patients who received vitamin E supplementation of 600 mg/day had a lower incidence of CIPN (risk ratio [RR] 0.31; 95% confidence interval [CI] 0.14–0.65; p = 0.002) than the placebo group. Vitamin E played a key role in decreasing the incidence of peripheral neuropathy in the cisplatin chemotherapy group (RR 0.28; 95% CI 0.14–0.54; p = 0.0001). Moreover, vitamin E supplementation significantly decreased patients’ sural amplitude after 3 rounds of chemotherapy (RR −2.66; 95% CI −5.09 to −0.24; p = 0.03) in contrast with that of placebo supplementation, while no significant difference was observed when patients were treated with vitamin E after 6 rounds of chemotherapy. In addition, the vitamin E-supplemented group had better improvement in the neurotoxicity score and lower incidence of reflexes and distal paraesthesias than the control group. Conclusion: Available data in this meta-analysis showed that vitamin E supplementation can confer modest improvement in the prevention of CIPN.