Watch-and-Wait After Immunochemotherapy in Locally Recurrent Nasopharyngeal Carcinoma

Inclusion Criteria: 1. Age ≥ 18 years, regardless of sex. 2. Treatment-naïve patients with newly diagnosed metastatic nasopharyngeal carcinoma (NPC). 3. Receiving immunotherapy. (or Treated with immunotherapy) 4. At least one measurable tumor lesion according to RECIST (Response Evaluation Criteria in Solid Tumors) version 1.1. 5. Adequate organ function. 6. Signed and dated informed consent form indicating that the patient (or legally authorized representative) has been informed of all pertinent aspects of the study. 7. Patients willing and able to comply with scheduled visits and study procedures. Exclusion Criteria: 1. Patients with distant metastasis of nasopharyngeal carcinoma. 2. Patients who have not received immunotherapy or chemotherapy. (Alternatively: No prior immunotherapy or chemotherapy.) 3. History of another active malignancy within the past 5 years, except for malignancies with a negligible risk of metastasis or death (e.g., expected 5-year overall survival \>90%) or malignancies treated with curative intent and with no evidence of disease (e.g., adequately treated carcinoma in situ of the cervix, basal cell or squamous cell carcinoma of the skin, localized prostate cancer treated with curative intent, ductal carcinoma in situ of the breast treated surgically with curative intent). 4. Lack of capacity to provide informed consent.