[Correlation of imaging-based staging to prognosis of nasopharyngeal carcinoma: computed tomography versus magnetic resonance imaging].

Background & Objective: Imaging results are important for clinical staging and irradiation target planning of nasopharyngeal carcinoma (NPC). This study tried to analyze the correlations of staging based on computed tomography (CT) and magnetic resonance imaging (MRI) before radiotherapy to prognosis of NPC.

Methods: Clinical data of 445 pathologically confirmed NPC patients with no metastasis were analyzed. CT was performed on 230 patients before treatmentû MRI was performed on 215 patients. All patients received conventional radiotherapy, and some locally advanced patients received additional chemotherapy. Kaplan-Meier and log-rank tests were used to analyze and compare the survival rates of the two groups. Cox model was used to analyze prognostic factors.

Results: The 1-, 2-, and 3-year overall survival rates were significantly lower in CT group than in MRI group (96.9% vs. 98.6%, 90.3% vs. 94.3%, 85.3% vs. 92.3%, Chi2 =6.305, P=0.012). The 1-, 2-, and 3-year disease-free and relapse-free survival rates were also significantly lower in CT group than in MRI group (P<0.05). Univariate analysis showed that clinical stage, N stage, imaging method and chemotherapy were prognostic factors of NPC. Multivariate analysis showed that clinical stage and imaging method were independent prognostic factors of NPC.

Conclusions: Determining target volume by MRI before radiotherapy can improve the survival rate and local control rate of NPC patients when compared with CT. Clinical stage and imaging method are independent prognostic factors of NPC patients.