Retropharyngeal lymph node metastasis in nasopharyngeal carcinoma: Prognostic value and staging categories

Purpose: To investigate the incidence, prognostic value, and staging categories of retropharyngeal lymph node (RLN) metastasis in nasopharyngeal carcinoma (NPC). Experimental Design: We did a retrospective review of the data from 749 biopsy-proved non-metastatic NPC patients. All patients had undergone contrast-enhanced computed tomography and had radiotherapy as their primary treatment. Results: The incidence of RLN metastasis was 51.5%. After adjusting for tumor (T) and node (N) classifications, a borderline significant difference of distant metastasis-free survival (DMFS) rates was observed between patients with or without RLN metastasis. In No disease, the presence of RLN metastasis was a significant independent predictor for overall survival (OS), loco-regional relapse-free survival, and DMFS in multivariate Cox modeling analysis. No significant difference was observed in all end points between patients with unilateral and bilateral RLN metastasis. The hazard ratios of death and distant failure for N-0 with RLN metastasis were similar to N-1. The survival curve of OS and DMFS for N-0 disease with RLN metastasis had approximated that of N-1 disease. The survival curve of OS for T-1 disease with RLN metastasis was approximately the same as T-2 disease. However, the survival curve of DMFS for T-1 disease with RLN metastasis was approximately the same as in T-3 disease. Conclusions: RLN metastasis has a tendency to affect the DMFS rates of patients with NPC. Retropharyngeal node involvement has a negative effect on the prognosis of No disease. RLN metastasis should be classified as N-1.