Survival impacts of different nodal characteristics and T-classification in N3 nasopharyngeal carcinoma patients

We investigated the survival impacts of various nodal characteristics and T-classification on nasopharyngeal carcinoma (NPC) patients with the 8th AJCC/UICC staging criteria N3.Pretreatment MRIs from 110 staged N3 NPC patients were reviewed. There were 23 T1, 25 T2, 32 T3, and 30 T4, respectively. All except one patient belonged to WHO type II pathology. All patients received curative radiotherapy 68.0-76.8 Gy plus different chemotherapy, including induction, concurrent, adjuvant or any combination. Various endpoints, including OS (overall survival), DFS (disease-free survival), LRFFS (locoregional failure-free survival), DMFFS (distant metastasis failure-free survival) were compared between different nodal characteristics and T-classification.There were no statistically significant differences in all analyzed survival curves between various nodal characteristics, including unilateral N3 vs. bilateral N3, "large" nodes (6 cm) alone vs. "low" nodes (below the caudal border of cricoid cartilage) alone vs. combined "large" and "low" nodes, risk score 1 vs. 2 vs. 3 vs. 4 (by counting the sum of "large" and "low" nodes in the same case), and radiologic extra-nodal extension. Patients with T4, compared with those of T1-3 have worse OS (5-year rates, 42.2% vs. 82.8%, P 0.0001), DFS (5-year rates, 43.9% vs. 68.9%, P = 0.0037), LRFFS (5-year rates, 69.3% vs. 82.7%, P = 0.0432), and DMFFS (5-year rates, 57.2% vs. 77.7%, P = 0.0163).Our results support merging previous N3a and N3b as a N3 category in the 8th edition new staging system. Patients with T4N3 diseases have extremely poor outcome and deserve to strengthen the treatment intensity in future trials.