Pseudomembrane Removal for Post-RT Nasopharyngeal Necrosis

Inclusion Criteria: * Voluntarily sign the informed consent form. * Age between 18 and 80 years. * ECOG performance status ≤ 2. * Prior radical radiotherapy with total dose ≥ 66 Gy. * Imaging or histopathology confirmed local recurrence and/or retropharyngeal lymph node recurrence, with or without cervical lymph node recurrence. * Re-irradiation with single dose \< 2.3 Gy and total dose ≥ 50 Gy. * Presence of pseudomembrane reaction on nasopharyngeal mucosa during or after re-irradiation. * Expected survival \> 1 year. * Induction chemotherapy, immunotherapy, concurrent chemotherapy, adjuvant chemotherapy, or radiotherapy alone are all permitted. Exclusion Criteria: * History of other malignancies within the past 5 years, except cured non-melanoma skin cancer or carcinoma in situ of the cervix. * Severe uncontrolled systemic diseases (e.g., uncontrolled infection, severe cardiovascular disease, uncontrolled diabetes). * Pregnant or breastfeeding women. * Known allergy to any equipment or medication used during endoscopy. * Inability to tolerate endoscopic procedure due to anatomical or medical reasons. * Concurrent participation in another interventional clinical trial. * Any condition that, in the investigator's judgment, would interfere with study compliance or outcome assessment.