Prophylaxis With Oral Zinc Sulfate Against Radiation Induced Oral Mucositis in Patients With Head and Neck Cancers: A Systematic Review and Meta-Analysis of Four Randomized Controlled Trials

Background: Oral mucositis is an inevitable and distressing adverse event faced by patients with head and neck cancer who were treated with irradiation. Although several studies have investigated the potential of oral zinc sulphate in preventing radiation induced oral mucositis in patients with head and neck cancers, however a conclusive result has not yet been found. Objective: The aim of the present study is to apprise whether oral zinc sulphate is effective in preventing radiation induced oral mucositis in patients with head and neck cancers. Methods: We electronically searched all potential citations in PubMed, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL) and EBSCO from their inception to December 2018. After searched and checked literatures, extracted data and appraised risk of bias, RevMan software version 5.3 was used to perform meta-analysis. Results: Four randomized controlled trials (RCTs) involving 162 patients were included. Meta-analysis showed that zinc sulphate didn’t decrease the incidence (RR [relative risk], 0.97; 95% CI [confidence interval], 0.74 to 1.28), and relieve the moderate and severe grade of radiation-induced oral mucositis (moderate and severe oral mucositis: RR, 0.84; 95% CI, 0.14 to 4.87; severe oral mucositis: RR, 0.43; 95% CI, 0.00 to 38.98). Qualitative analysis suggested that zinc sulphate was associated with onset of oral mucositis. Conclusions: Based on limited evidence, zinc sulphate may not have the benefit in prophylaxis against radiation induced oral mucositis in patients with head and neck cancers. However, further RCTs with larger sample size and more rigorous methodology are needed to enhance the evidence of results.