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 patients, who were treated with irradiation for head and neck cancer, face. Although several studies have investigated the potential of oral zinc sulfate in preventing radiation-induced oral mucositis in patients with head and neck cancers, conclusive results have not yet been found. Objective: The aim of the present study is to determine whether oral zinc sulfate 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 the search 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. A meta-analysis showed that zinc sulfate did not decrease the incidence (RR [relative risk], 0.97; 95% CI [confidence interval], 0.74-1.28), and did not relieve the moderate and severe grade of radiation induced oral mucositis (moderate and severe oral mucositis: RR, 0.84; 95% CI, 0.14-4.87; severe oral mucositis: RR, 0.43; 95% CI, 0.00-38.98). A qualitative analysis suggested that zinc sulfate was associated with the onset of oral mucositis. Conclusions: Based on limited evidence, zinc sulfate may not have the benefit of prophylaxis against radiation-induced oral mucositis, in patients with head and neck cancers. However, further RCTs with larger sample sizes and more rigorous methodologies are needed to enhance the evidence of these results.