A Real-world Study of the Efficacy and Safety of PD-1 Inhibitors Combined With Chemoradiotherapy in Lung Metastatic Nasopharyngeal Carcinoma

Inclusion Criteria: 1. age of at least 18 years; 2. Karnofsky Performance Status (KPS) ≥60; 3. histologically confirmed nasopharyngeal squamous carcinoma; 4. metastatic disease after primary standard treatment (patients who had metastatic diseases over six months after treatment); 5. at least 1 measurable metastatic lesions in lung or mediastinal or pleura (imaging for distant metastases with FDG-PET/CT or chest/abdomen CT with contrast); 6. adequate renal , liver and bone marrow function. Exclusion Criteria: 1. previous treatment with an immune checkpoint inhibitor; 2. recurrent disease; 3. previous systemic chemotherapy for metastatic disease; 4. symptomatic central nervous system metastases; 5. a history of non-infectious pneumonitis that required glucocorticoids, or active autoimmune disease; 6. severe organ dysfunction or not suitable for chemoradiotherapy; 7. individuals that had serious kidney, heart, blood, nervous system, or liver diseases or psychiatric disorders; 8. individuals that had taken part in any other clinical trials testing other drugs within 3 months of the present study; 9. other patients whom researchers deemed unsuitable to participate in the study.