Concurrent Chemoradiotherapy With or Without Metronomic Capecitabine in High-Risk T1-2N1M0 NPC

Inclusion Criteria: 1. Aged 18 to 70 years. 2. Pathologically confirmed, previously untreated "non-keratinizing carcinoma (WHO types II/III)" of the nasopharynx. 3. Diagnosed as stage T1-2N1M0 (Stage IB) according to the 9th edition of the American Joint Committee on Cancer/Union for International Cancer Control (AJCC/UICC) staging system. 4. Presence of at least one of the following high-risk lymph node features: more than three metastatic cervical lymph nodes (retropharyngeal lymph nodes are not counted), presence of nodal necrosis, or presence of nodal confluence. 5. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. 6. Detectable baseline plasma EBV DNA, with EBV DNA remaining detectable at any time point from the second week after the start of concurrent chemoradiotherapy until the end of radiotherapy. 7. Adequate bone marrow function, liver and renal function. Exclusion Criteria: 1. Intolerance or allergy to capecitabine. 2. Conditions that may interfere with the absorption or adherence to oral medication, such as dysphagia, chronic diarrhea, or intestinal obstruction. 3. Administration of biologic therapy or immunotherapy during or prior to radiotherapy. 4. Pregnancy or lactation (a pregnancy test should be considered for women of childbearing potential, and emphasis must be placed on effective contraception during the treatment period). 5. Any concurrent severe or uncontrolled medical condition that would pose an unacceptable risk or compromise protocol compliance, including but not limited to untreated unstable cardiac disease, renal disease, chronic hepatitis, poorly controlled diabetes (fasting blood glucose \>1.5×ULN), or mood disorders.