Sentinel node necrosis is a negative prognostic factor in patients with nasopharyngeal carcinoma: a magnetic resonance imaging study of 252 patients

Purpose We explored the patterns of sentinel node metastasis and investigated the prognostic value of sentinel node necrosis (SNN) in patients with nasopharyngeal carcinoma (NPC), based on magnetic resonance imaging (MRI). Methods This retrospective study enrolled 252 patients at our institution who had metastatic lymph nodes from biopsy-confirmed NPC and who were treated with definitive radiation therapy, with or without chemotherapy. All participants underwent MRI before treatment, and the resulting images were reviewed to evaluate lymph node status. The patients were divided into SNN and non-SNN groups. Overall survival (OS), tumour-free survival (TFS), regional relapse-free survival (RRFS), and distant metastasis-free survival (DMFS) were calculated by the Kaplan-Meier method, and differences were compared using the log-rank test. Factors predictive of outcome were determined by univariate and multivariate analysis. Results Of the 252 patients, 189 (75%) had retropharyngeal lymph node metastasis, and 189 (75%) had level IIA or IIB lymph node necrosis. The incidence of SNN was 43.4% (91 of 210 patients with lymph node metastasis or necrosis, or both). After a median follow-up of 54 months, the 5-year rates of OS, TFS, RRFS, and DMFS in the SNN and non-SNN groups were, respectively, 79.4% and 95.3%, 73.5% and 93.3%, 80.4% and 96.6%, and 75.5% and 95.3% (all p < 0.01). Age greater than 40 years, SNN, T stage, and N stage were significant independent negative prognostic factors for OS, TFS, RRFS, and DMFS. Conclusions Metastatic retropharyngeal lymph nodes and necrotic level II nodes both seem to act as sentinels. Sentinel node necrosis is an negative prognostic factor in patients with NPC. Patients with SNN have a worse prognosis.