Evaluation of Three-year Overall and Disease-free Survival in Iranian Patients with Nasopharyngeal Carcinoma Treated by Intensity-modulated Radiotherapy (IMRT): A Historical Cohort Single Center Study

Background: The aim of this study was to evaluate and analyze disease-free survival (DFS) and overall survival (OS) after intensity-modulated radiotherapy (IMRT) for Iranian patients with nasopharyngeal carcinoma (NC). Methods: In this historical cohort study, 65 non-metastatic patients treated for NC with IMRT were selected and reviewed at the Shohadai-e-Tajrish Hospital between October 2017 and October 2019. Chemotherapy was given either as induction, concurrent, or adjuvant therapy in all cases. Three years of DFS and OS were calculated according to Kaplan-Meier and compared with the Pearson Correlation Test. Results: The mean age of patients was 43.38 years. The three-year DFS and OS rates were 95.72%, 92.32%, 72.73%, 73.26%, and 100%, 84.61%, 90.90%, and 79.41% in stage I, II, III, and IV patients, respectively (P = 0.119, P = 0.155). The total three-year DFS rate and the total three-year OS rate were 76.47% and 84.60% in all cases. Based on the Pearson Correlation Test, it was a significant correlation between the duration of IMRT time and three-year DFS (correlation=0.138, P = 0.017) and the number of concurrent cycles of chemotherapy with IMRT (correlation=0.375, P = 0.002). It was not a significant correlation between total time duration, MRI response, induction chemotherapy, age, sex, and the three-year DFS. There was a significant correlation between total time duration and three-year OS (correlation=0.263, P = 0.040) and the number of concurrent cycles of chemotherapy with IMRT and three-year OS (correlation=0.334, P = 0.007). It was not a significant correlation between the duration of IMRT time, MRI response, induction chemotherapy, age, sex, and the three-year OS. Conclusions: Our findings showed that IMRT with concurrent chemo-radiotherapy has the three-year DFS and OS, which were comparable with the other published results. We emphasize the number of concurrent cycles of chemotherapy with IMRT, which have an important role in both three-year DFS and OS. The duration of IMRT time has also an important role in the three-year DFS but not in the three-year OS. A longer follow-up for the patients to evaluate 10-year DFS and OS is recommended.