OBJECTIVE: To investigate the relationship between the UH_2-U ratio,5- Fu concentration and toxicity in 20 nasopharynx patients and to discover if the UH_2-U ratio could be used as an indication to adjust the dose of 5Fu or to change the therapy regimen.

• 目的：评价内源性二氢尿嘧啶（UH2）与尿嘧啶（U）的比值（RUH2/U）5－氟尿嘧啶（5－Fu）化疗方案中与5－氟尿嘧啶血药浓度（C5Fi）、消化系统毒性级别的相关关系，为5－氟尿嘧啶化疗方案的调整及剂量个体化提供依据。