Clinical outcomes and patterns of failure after intensity-modulated radiotherapy for T4 nasopharyngeal carcinoma.

The goal of this study is to study and report the clinical outcomes and patterns of failure after intensity-modulated radiotherapy (IMRT) for T4 nasopharyngeal carcinoma (NPC). A total of 70 patients treated with IMRT between 2004 and 2009 were eligible for study inclusion. According to the staging system of 2010 AJCC, all the primary tumors were attributed to T4 stage, while the distribution of disease by N stage was N0 in 2, N1 in 23, N2 in 39, N3a in 1, and N3b in 5. The location and extent of locoregional failures were transferred to the pretreatment planning computed tomography for dosimetry analysis. The median follow-up period was 26.8 (range, 4-78) months. The overall 2-year local failure-free survival, regional failure-free survival, distant failure-free survival, and overall survival rate was 82.1%, 92.3%, 73.8%, and 82.5%, respectively. Thirty-three patients had developed treatment failure. Of the 33 patients, 11, 2, and 15 had developed local failure, regional failure, and distant metastasis, respectively, 2 had developed locoregional failure, 1 had developed distant metastasis and failure at the primary, and 2 had developed distant metastasis and failure at the primary and nodal site. Eight of the locoregional failures were marginal. The results of treating T4 NPC with IMRT were excellent. Advanced T4 disease remained difficult to treat. One possible strategy is to lessen the dose constraint criteria of selected neurologic structures. Distant metastasis remains the most difficult treatment challenge for patients with T4 NPC at present, and more effective systemic chemotherapy should be explored.