This is an randomized, controlled, multicenter phase 3 clinical trial. The purpose of this study is to evaluate the efficacy and safety of single-agent capecitabine as adjuvant chemotherapy in locoregionally advanced nasopharyngeal carcinoma (NPC).

In this study, NPC patients (stage III-IV A, except T3-4 N0 and T3 N1) who finished the curative radiotherapy will be randomized to the observation group and capecitabine group (650 mg/m2 bid, p.o.，d1-21，q3wks; continued until disease progression, unacceptable toxicity, or over 1 year). The primary endpoint is progression-free survival (PFS). Secondary end points include overall survival (OS), distant failure-free survival (D-FFS), locoregional failure-free survival (LR-FFS), toxic effects, and quality of life (QOL). All efficacy analyses are conducted in the intention-to-treat population, and the safety population include only patients who receive their randomly assigned treatment.

Inclusion Criteria:

1. Age 18-65
2. Performance status of Eastern Cooperative Oncology Group (ECOG) grade 0 or 1
3. Tumor staged as American Joint Committee on Cance (AJCC) III-IV A (except T3-4 N0, T3 N1), with newly histologically confirmed non-keratinizing NPC
4. Within 12-16weeks after completion of the recommended curative radiotherapy treatment
5. No clinical evidence of persistent loco-regional disease or distant metastases after radiotherapy
6. Complete the recommended concurrent chemotherapy ± induction chemotherapy
7. Adequate hematologic (neutrophil count > 1.5×10^9/L, hemoglobin > 90g/L and platelet count > 100×10^9/L), hepatic (alanine aminotransferase, aspartate aminotransferase ≤ 1.5×ULN, bilirubin ≤ 1.5×ULN, alkaline phosphatase < 2.5×ULN) and renal function (creatinine clearance > 50 ml/min)
8. Patients must be informed of the investigational nature of this study and give written informed consent.

Exclusion Criteria:

1. Patients who could not tolerate or allergic to capecitabine.
2. Illness that would interfere with oral medication, including dysphagia, chronic diarrhea, or ileus
3. Prior malignancy except adequately treated basal cell or squamous cell skin cancer, in situ cervical cancer.
4. Pregnancy or lactation (consider pregnancy test in women of child-bearing age and emphasize effective contraception during the treatment period).
5. Patients who received surgery treatment, biotherapy or immunotherapy during or before radiotherapy.
6. Patients who are receiving or highly likely to receive other chemotherapy treatment, biotherapy or immunotherapy.
7. History of previous radiotherapy before the curative radiotherapy (except for non-melanomatous skin cancers outside intended RT treatment volume).
8. Prior chemotherapy or surgery (except diagnostic) to primary tumor or nodes before the curative radiotherapy
9. Any severe intercurrent disease, which may bring unacceptable risk or affect the compliance of the trial, for example, unstable cardiac disease requiring treatment, renal disease, chronic hepatitis, diabetes with poor control (fasting plasma glucose > 1.5×ULN), and emotional disturbance.