The purpose of this study is to evaluate whether dietary nitrate supplementation could improve the salivary flow for nasopharyngeal carcinoma patients receiving concurrent chemo-radiation therapy.

Thirty patients diagnosed as nasopharyngeal carcinoma will be recruited. Nitrate supplement(Sodium nitrate: 0.5 mmol/kgbodyweight,bid) or placebo(sodium chloride: 0.5 mmol/kgbodyweight,bid) will be provided to the patients from 7 days before radiotherapy to one month after the finish of radiotherapy . The salivary flow and plasma nitrate levels will be determined before the course of nitrate supplementation and radiotherapy,before the course of radiotherapy,post the course of radiotherapy immediately and one month after the finish of radiotherapy.

Inclusion Criteria:

• Patients with newly diagnosed stages III-IVb (UICC 2002) nasopharyngeal carcinomas, will be recruited.

Exclusion Criteria:

• Patients with local invasion or metastatic foci in salivary glands, detected by MRI and positron emission computed tomography(PET-CT) prior to treatment, were excluded, as were patients suffering from diseases, such as Sjogren's syndrome, or with a history of surgery to major salivary glands, or prior head and neck radiotherapy.