Protective effects of vitamin E on chemotherapy-induced peripheral neuropathy: A meta-analysis of rando-mized controlled trials

Purpose: This study aimed to investigate the neuroprotective effects of vitamin E for preventing chemotherapy-induced peripheral neuropathy (CIPN). Methods: A comprehensive search from 1973 through July 2011 identified randomized controlled trials (RCTs) that reported the preventive effects of vitamin E on CIPN. The relative risk (RR) of CIPN with vitamin E supplementation, comparedwith placebo, was assessed with the Bayesian random effect model and expressed as RR with a 95 %credible-interval (CrI). Bayesian outcome probabilities were calculated as the probability (P) of RR <1. Results: Five RCTs, involving 319 patients, were identified. Upon pooling these RCTs, vitamin E supplementation (300-600 mg/day) had a significant effect on CIPN prevention (RR 0.43; 95 % CrI 0.10-1.00, P = 97.5 %). Subgroup analysis by chemotherapeutic agent type was only available for cisplatin and showed that vitamin E supplementation significantly reduced the incidence of CIPN (RR 0.26; 95 % CrI 0.06-0.89, P = 98.1 %). Furthermore, there were no adverse effects caused by vitamin E supplementation in any of the RCTs. Conclusion: Available data included in this meta-analysis show that vitamin E supplementation might significantly prevent CIPN. Currently, however, the data are insufficient to confidently conclude the true value. Large-scale, rigorously designed RCTs are needed to confirm the role of vitamin E supplementation in CIPN prevention.