Abstract
OBJECTIVE: The aim of this study was to investigate the alteration of drug-resistant proteins in nasopharyngeal carcinoma (NPC) after intensity-modulated radiation therapy (IMRT) with or without chemotherapy and its correlation with clinicopathologic features and short-term prognosis. METHODS: Eligible NPC patients receiving IMRT with or without chemotherapy were studied. Tumor tissues from patients before treatment and at 2/3 of IMRT were obtained, and drug resistance proteins, P-glycoprotein (P-gp), multidrug resistance-associated protein (MRP), lung resistance protein (LRP), and glutathione S-transferase π (GST-π) were detected. Meanwhile, the clinicopathological data of the patients were collected and statistically analyzed. The short-term prognosis of the patients was observed and recorded, and the correlation between progression-free survival (PFS) and positive drug-resistant proteins was analyzed. RESULTS: Before treatment, the positive rates of P-gp, MRP, LRP, and GST-π among the 43 NPC patients were 30.23%, 16.28%, 20.93%, and 34.88%, respectively; after treatment, the positive rates of P-gp and MRP were 65.12% and 41.86%, respectively (P-gp, P < 0.001; MRP, P = 0.009). Significantly higher positive rates of P-gp were observed only after treatment than before treatment in the IMRT-alone group (n = 18) and IMRT/chemotherapy group (n = 25). The intensity of P-gp, MRP and GST-π positive expression was increased in patients treated with IMRT/chemotherapy compared to pre-treatment. No correlation between positive expression of drug-resistant proteins and lymphatic metastasis was observed. Patients with P-gp and GST-π positivity had a more pronounced decrease in PFS. CONCLUSION: P-gp, MRP, and GST-π are increased in NPC patients after IMRT with or without chemotherapy and are closely associated with poor short-term prognosis of patients.