ABSTRACT
<p><b>OBJECTIVE</b>To study the relationship between multidrug-resistant (MDR) expression in nasopharyngeal carcinoma (NPC) and its sensitivity to chemotherapy.</p><p><b>METHODS</b>The specimens of 23 NPC cases were studied by immunohistochemistry with monoclonal antibody of P-glycoprotein (P-gp), multidrug resistance relation protein (MRP), lung-resistance related protein (LRP), topoisomerase II (Topo II), thymidylate synthase (TS), glutathione-S-transferase (GST-pi). Among them, 20 specimens were taken from primary NPC lesion which were treated with two course of cisplatin (DDP) and 5-fluorouracil (5-FU), 3 specimens were taken from cervical lymph-node of recurrent NPC patients who were treated by radical dissection.</p><p><b>RESULTS</b>Various MDR parameters were expressed differently in 22 cases except for 1 clear cell carcinoma case. The difference was statistically significant (P < 0.05). However, there were no significant difference of MDR expression either among various carcinoma pathomorphology cell groups or among different clinical stage groups. Expression of LRP and TS were found in 10 and 14 cases respectively and the chemotherapy responders rates were 20% (2/10) and 28.5% (4/14) respectively. While the chemotherapy responders rates were 70% (7/10) and 5/6 in cases without expression. There was significant difference (P < 0.001, and P < 0.05).</p><p><b>CONCLUSION</b>The NPC patients with LRP and TS expression may be less sensitive to chemotherapy with DDP + 5-FU.</p>