Maintenance Therapy of Apatinib After Chemoradiotherapy in Metastatic Nasopharyngeal Carcinoma

Inclusion Criteria: * Male and female patients aged ranging from 18 to 75 years old. * Naive or recurrent Nasopharyngeal Carcinoma with metastasis after chemotherapy or radiotherapy. * Eastern Cooperative Oncology Group (ECOG) performance status of 0 - 2. * Adequate hematologic (neutrophil count\>=1.5×109/L, hemoglobin\>=80g/L, platelets\>=80×109/L), hepatic function (aspartate transaminase (AST) \& alanine transaminase(ALT) =\<upper normal limit(UNL) x2, bilirubin level =\< UNL x 1.5). * Adequate renal function (creatinine clearance ≥ 60 mL/min). * Patients have the ability to understand and voluntarily sign the informed consent, and allow adequate follow-up. Exclusion Criteria: * Previously, patients did receive the therapy of Apatinib or other VEGFR inhibitor, such as Sorafenib, Sunitinib. * Difficulties in taking pills (inability to swallow tablets,GI tract resection, chronic bacillary diarrhea and intestinal obstruction). * Bleeding tendency or coagulation disorders. * with brain metastases. * Uncontrolled hypertension (systolic pressure\>150 mmHg , or diastolic pressure\> 90 mmHg). * Urine protein≥++, or urine protein in 24 hours≥1.0g * Severe uncured wounds, ulcers or fracture. * Pregnant or breast-feeding. * Patients with epilepsy who need to take medicine (such as steroids or anti epilepsy agents). * Patients have these symptoms, such as neurological diseases, mental illness, serious infection. * The researcher believe that the Patient is not suitable to participate in the study.