临床上对肿瘤患者进行化疗失败的重要原因是瘤细胞对化疗药物产生耐受性 [1] ,多药耐药 (MDR)就是耐药的一个主要类型 [2 ] ,其实质是 MDR基因 mdr- 1表达升高 ,导致细胞内药物积聚减少 [3] 。我们选择食管癌患者手术切除的标本组织 ,采用 RT- PCR方法检测其表达水平 ,探讨 MDR The clinically important reason for the failure of chemotherapy for cancer patients is that the tumor cells are resistant to chemotherapeutic drugs [1]. Multidrug resistance (MDR) is a major type of drug resistance [2]. The substance is the mDR-gene of MDR. 1 Increased expression leads to decreased intracellular drug accumulation [3]. We selected specimens from esophageal cancer patients undergoing surgical resection and examined their expression levels using RT-PCR to explore MDRs.