A Multi-center, Randomized, Double-blind, Phase III Clinical Trial of Leucogen Versus Placebo on Leukocyte and Platelet Whole-course Management Assisted by PFLL Chemotherapy in the Treatment of Stage IV, Recurrent or Metastatic NPC

5-fu: 200mg/m2/d, continuous intravenous infusion on the 1st to 30th day of each cycle.

30mg/m2, used on the 1st and 28th day of each cycle.

2 tablets/dose 3 times for peri-chemotherapy prophylaxis and inter-chemotherapy period, 3 tablets/dose 3 times daily during chemotherapy, and continued to be given orally 2 tablets/dose 3 times daily for 4 weeks after the end of chemotherapy.

40 mg/dose was used 3 times for peri-chemotherapy prophylaxis and inter-chemotherapy period, and 60 mg/dose was used 3 times daily during chemotherapy, and 40 mg/dose was continued orally 3 times daily for 4 weeks after the end of chemotherapy.