Discrepancy of the effects of zinc supplementation on the prevention of radiotherapy-induced mucositis between patients with nasopharyngeal carcinoma and those with oral cancers: Subgroup analysis of a double-blind, randomized study

The purpose of this study was to determine the effect of zinc supplementation on radiation-induced mucositis in patients with nasopharyngeal carcinoma (NPC) and those with oral cancers (OC). A total of 100 patients with head and neck cancers engaged in a randomized double blind study. All participants were placed into two randomized groups (experimental and control). The experimental group received a standard dose of zinc supplements, and the control group was given a placebo. Subgroup analyses were performed between 40 NPC and 43 OC patients. It was found that patients with OC in the control group developed Grade 2 and Grade 3 mucositis sooner than those in the experimental group. However, the benefits were not found to extend to patients with NPC. The results indicated that zinc supplementation prescribed in conjunction with radiotherapy postponed the development of severe mucositis solely for patients with OC. The pretreatment oral mucosa condition and areca chewing habit might account for such discrepancy.