Influence of MRI abnormality in skull base bone on prognosis of nasopharyngeal carcinoma.

PURPOSE: To evaluate the influence of skull base bone (SBB) abnormality showed by MRI on prognosis of nasopharyngeal carcinoma (NPC). PATIENTS AND METHODS: From March 1993 to December 1998, 122 NPC patients received prime radiotherapy treatment. All of them were proved pathologically and checked by magnetic resonance imaging (MRI). Every patient received radiation through conjoint facio-cervical field and conventional dose-fractionation schedules. The total dose to the primary tumor was 60-75 Gy (median, 70 Gy). The Kaplan-Meier method, the Log-rank test and the Cox regression model were used to evaluate the significance of prognostic factors on NPC patient survival. RESULTS: The overall median survival period was 50 (6-92) months, and the 1, 3 and 5 year-survival rates were, respectively, 99.2%, 87.9%, and 73.3%. The 1, 3, and 5 year-survival rates of abnormality and normality of the SBB on MRI were 98.9%, 87.2%, 71.9%, and 100.0%, 89.8%, 77.0%, respectively (P = 0.4233). Gender, age, head pain, SBB abnormality, cranial nerve palsy, cervical lymphadenopathy and primary tumor extent were analyzed with the Cox regression model and SBB abnormality on MRI did not prove to have statistical significance (P = 0.6934). According to the analysis of regrouping, patients with SBB abnormalities > or =2 sites have a worse prognosis (P = 0.0427). Then, the above seven factors are analyzed by Cox regression model and the result had statistical significance (P = 0.0385). CONCLUSION: The SBB abnormality on MRI is of no obvious influence on prognosis of NPC. However, when SBB abnormality sites were > or =2, there is obvious statistical significance on the prognosis.