Carbon-Ion Radiotherapy Plus Camrelizumab for Locally Recurrent Nasopharyngeal Carcinoma

Inclusion Criteria: * Completed a definitive course of intensity-modulated photon radiation therapy (IMRT) to a total dose of ≥ 66 Gy * Recurrence at nasopharynx diagnosed more than 6 months after the initial course of IMRT * Patients with neck lymphadenopathy should receive neck dissection before randomization * With measurable lesion on contrast MR scan * Age ≥ 18 and \< 70 years of age * ECOG score: 0-1 * Leucocyte count ≥ 4000/µL, neutrocyte count ≥ 2000/µL, platelet count ≥ 100000/µL, hemoglobin ≥ 90g/L * Alanine Aminotransferase (ALT), and Aspartate Aminotransferase (AST) \< 1.5×upper limit of normal (ULN), alkaline phosphatase \< 2.5×ULN, bilirubin ≤ ULN, serum creatinine ≤ ULN, creatinine clearance ≥ 60ml/min * Willing to accept adequate contraception * Ability to understand the nature of the clinical trial and sign the written informed consent Exclusion Criteria: * Presence of distant metastasis * Previously received radioactive particle implantation * Prior malignancy within 5 years before randomization, except for adequately treated basal cell or squamous cell skin cancer, in-situ cervical cancer * Patients who received local (such as surgery and cryotherapy) or systemic treatment, except for induction chemotherapy after diagnosis of recurrence * With uncontrolled active infection * With pneumonia * With autoimmune disease * With a known history of testing positive for human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS) * Hepatitis B virus (HBV) DNA ≥ 500IU/mL for patients with positive HBV surface antigen, positive hepatitis C virus RNA for patients with positive HCV antigen * Previously treated by immune checkpoint inhibitors * Medical conditions requiring treatment of antibiotics and/or corticosteroid * Treated with ≥ 5 days antibiotics one month before start of immunotherapy * With known allergy to any of the study drugs * Pregnant or lactating women * Any severe intercurrent disease that may interfere with the current study