Radiation Therapy for Nasopharyngeal Carcinoma: Predictability of Treatment Outcomes at Interim Re-assessment

Purpose/Objective(s): To evaluate the effectiveness and toxicities in T4 nasopharyngeal carcinoma (NPC) using intensity modulated radiation therapy (IMRT) combined with chemotherapy. Materials/Methods: This is a retrospective analysis of 81 patients treatedwith intensity modulated radiation therapy (IMRT). All the primary tumors were attributed to T4 stage according to the AJCC2010 staging system. In addition, the distribution of disease by N stage was N0 in 13.6%, N1 in 30.9%, N2 in 37%, and N3 in 18.5%. Cisplatin-based chemotherapy was offered to all patients. Radiation therapy-related toxicities were graded according to the Acute and the Late Radiation Morbidity Scoring Criteria of the Radiation Therapy Oncology Group (RTOG) scoring criteria. Chemotherapy-related toxicities weregradedbyNationalCancer InstituteCommonTerminologyCriteria (NCICTC) version 3.0. Prognostic factors were assessed by univariate analysis. Results: With a median follow-up of 37 months, 12 patients experienced local regional failure and total distant metastasis occurred in 18 patients, representing the major mode of failure. Ten patients died. Among them, 70% died of distant metastasis. The 3-year actuarial rates of local failurefree survival (LFFS), regional failure-free survival (RFFS), distant failurefree survival (DFFS), overall survival (OS), and progression-free survival (PFS) were 83.8%, 97.4%, 81.3%, 90%, and 69.7%, respectively. Acute and late toxicities were mild or moderate. Conclusions: IMRT provides excellent local-regional control for T4 NPC. Distant metastasis remains the major cause of treatment failure. Further explorations of the sequence and regimenof systemic therapy are needed in the future. Author Disclosure: H. Ying: None. F. Kong: None.