Randomized, Double-blind, Placebo-Controlled Trial of Shuanghuabaihe Tablets to Prevent Oral Mucositis in Patients with Nasopharyngeal Cancer Undergoing ChemoradiotherapyBaomin Zheng Xiaodong Zhu Mengzhong Liu Zhenzhou Yang Ling Yang Jinyi Lang Mei Shi Gang Wu Xia He Xiaozhong Chen Xuping Xi Dan Zhao Guangying Zhu