Abstract
PurposesTo evaluate retropharyngeal lymph node metastasis on N stage of nasopharyngeal carcinoma (NPC).MethodsNPC patients were extracted from the Surveillance, Epidemiology, and End Results database between 2004 and 2016. Pathologically confirmed patients with complete data of retropharyngeal lymph node metastasis were investigated. The included patients were divided into N1a and N1b groups. Overall survival (OS) and cancer-specific survival (CSS) were assessed using the Kaplan–Meier method and propensity score matching (PSM) analyses.ResultsThis retrospective cohort study examined 759 patients: 70 who were stage N1a and 689 who were stage N1b. Before PSM, N1a group was associated with similar 5-year OS (77.7% vs. 72.4%; P = 0.15) and CSS (85.6% vs. 79.9%; P = 0.09) compared to N1b group. After PSM, a similar OS (75.0% vs. 60.7%; P = 0.12) was found between the radiotherapy and chemoradiotherapy groups. However, N1a group showed a better 5-year CSS (83.8% vs. 71.1%; P = 0.04) compared to N1b group. Stage N1b was an independent risk prognostic factor for CSS (hazard ratio = 2.54, 95% confidence interval: 1.02–6.34; P = 0.04).ConclusionsOS was not different between N1a and N1b groups. Retropharyngeal lymph node metastasis defined as stage N1 of the 8th edition American Joint Committee on Cancer staging system is reasonable.
Highlights
An accurate staging system is crucial for clinicians to formulate treatment plans and evaluate treatment outcomes
Stage N1b was an independent risk prognostic factor for cancer-specific survival (CSS)
Retropharyngeal lymph node metastasis defined as stage N1 of the 8th edition American Joint Committee on Cancer staging system is reasonable
Summary
An accurate staging system is crucial for clinicians to formulate treatment plans and evaluate treatment outcomes. Unilateral cervical lymph nodes 3 cm above caudal border of cricoid cartilage was classified as stage N1b. Pan et al [3] found that the 5-year distant metastasis-free survival were not different between stage N1a and N1b of the 2008 Chinese edition. With the purpose of simplification of unnecessary subgroups, the 8th edition AJCC staging system defied stage N1 as a whole group including retropharyngeal nodes metastasis and unilateral cervical lymph nodes 6 cm above caudal border of cricoid cartilage. This raises a question of whether overall survival (OS) between stage N1a and N1b is different. We conducted this retrospective cohort study to assess the difference of OS between stage N1a and N1b
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