Objective: Nasopharyngeal carcinoma (NPC) is one of the dominant cancers in South China and Taiwan. Although NPC is highly chemosensitive, the use of chemotherapy for treating patients with recurrent or metastatic NPC has not been very successful. The emergence of drug resistance may be one of the major reasons. However, the mechanisms of drug resistance of NPC have never been addressed before. In this study, we sought to clarify the role of classical drug resistance markers in predicting the chemosensitivity and the prognosis of patients with advanced NPC.
Methods: In a cohort of 202 consecutive patients diagnosed at the Department of Pathology of the National Taiwan University Hospital, 44 patients with adequately preserved pretreatment tumor tissues and complete clinical information regarding the details of chemotherapy and tumor response were identified. The expression of multidrug resistance (MDR1), glutathione-S-transferase-pi (GSTpi), and p53 were determined by immunohistochemistry. Tumor response to chemotherapy and survival of the patients were the endpoints of this analysis.
Results: Thirty-four patients received cisplatin-based regimens, and 28 of them were enrolled in a prospective trial using a doxorubicin-containing regimen. The overall response rate was 70%. Expression of MDR1 was seen in only 5 cases (11%) and was associated with a significantly worse overall survival, yet did not appear to predict chemoresistance to the doxorubicin-containing regimen. Overexpression of p53 was seen in 22 patients, and surprisingly, was correlated with chemoresponse and a trend towards better survival. GSTpi expression was demonstrated in 13 cases (30%) and was not correlated with chemoresistance to cisplatin-containing regimens and overall survival.
Conclusion: In this relatively small cohort, positive MDR1 immunostaining predicted a poor overall survival for recurrent or metastatic NPC patients receiving chemotherapy. Overexpression of p53 by immunohistochemical staining, however, was associated with a better response rate to systemic chemotherapy and a trend towards better survival.
Copyright 2002 S. Karger AG, Basel