Main Session
Sep 29
PQA 07 - Head and Neck Cancer, Lung Cancer/Thoracic Malignancies, and Nursing and Supportive Care

3537 - Risk Stratification of Advanced Extranodal Extension in Retropharyngeal Lymph Nodes for Nasopharyngeal Carcinoma: A Multi-Center Study

03:45pm - 05:00pm ET
Poster Hall - Exhibit Hall A
Screen: 8
POSTER

Presenter(s)

Junyi Liu, MB - Department of Radiation Oncology, Jiangsu Cancer Hospital/Jiangsu Institute of Cancer Research/The Affiliated Cancer Hospital of Nanjing Medical University, Nanjing, jiangsu

J. Liu1,2, B. Lu1, T. Bu1,2, T. Jin1, T. Qiu1, C. He1, H. Zhou3, X. Jiang1,2, J. Wu1, S. Huang1, X. J. Du4, J. Gao5, X. Chen6, Y. Zhu7, X. He1, and L. Wu1,2; 1Department of Radiation Oncology, Nanjing Medical University Affiliated Cancer Hospital, Jiangsu Cancer Hospital and Jiangsu Institute of Cancer Research, Nanjing 210009, Nanjing, Jiangsu, China, 2Jiangsu Key Laboratory of Innovative Cancer Diagnosis & Therapeutics, Nanjing, Jiangsu, China, 3Department of Radiation Oncology, The Affiliated BenQ Hospital of Nanjing Medical University, Nanjing, China, 4Department of Radiation Oncology, State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer,Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, China, 5Department of Radiation Oncology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China, 6Department of Radiation Oncology, Zhejiang Cancer Hospital, Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, China, 7Department of Radiology, Nanjing Medical University Affiliated Cancer Hospital, Jiangsu Cancer Hospital and Jiangsu Institute of Cancer Research, Nanjing 210009, Nanjing, Jiangsu, China

Purpose/Objective(s):

This study aimed to refine risk stratification of advanced extranodal extension (ENE) in retropharyngeal lymph nodes (RLNs) and evaluate its prognostic significance.

Materials/Methods:

A total of 1,373 non-metastatic NPC patients at three centers between 2011 and 2021 were retrospectively enrolled. For advanced RLN ENE, we documented all involved structures, maximum axial diameter (MAD), presence of lymph node necrosis (LNN), and bilaterality. High-risk structures were identified using adjusted hazard ratios (AHRs) and least absolute shrinkage and selection operator (LASSO)–Cox models. Multivariable Cox models adjusted for confounding factors and Kaplan-Meier curves were used to evaluate the correlations between nodal features and overall survival (OS), progression-free survival (PFS), locoregional relapse-free survival (LRRFS), and distant metastasis-free survival (DMFS).

Results:

Of the 1,373 patients, 1061 (77.3%) had RLN metastasis, including 168 (12.2%) with advanced RLN ENE. Based on ranked AHRs, involvement of interval structures (external carotid artery, vertebral vessels, and longissimus cervicis muscle), lower cranial nerves region, internal jugular vein, and longus capitis muscle was classified as the high-risk structure group, whereas isolated internal carotid artery involvement was assigned to the low-risk group; these findings were supported by the LASSO–Cox model. Advanced RLN ENE with high-risk structure involvement or LNN—both associated with significantly worse survival—was defined as high-risk RLN ENE. High-risk RLN ENE was an independent adverse prognostic factor for NPC (AHROS:1.69, 95%CI:1.18-2.41, p=0.004). N1/N2 patients with high-risk RLN ENE had survival outcomes comparable to those of N3 patients (AHROS = 0.77, 95%CI: 0.42–1.42, p = 0.402; AHROS = 0.68, 95%CI: 0.35–1.31, p = 0.247).

Conclusion:

High-risk RLN ENE is an independent adverse prognostic factor in NPC. N1/N2 patients with high-risk RLN ENE exhibit N3-like survival, supporting its potential incorporation into future refinements of N staging.

a confounding factors include age, sex, T classification (T4 vs. T3 vs. T2 vs. T1), and treatment modality (induction or concurrent chemotherapy)
Table. Multivariate analysis of prognostic factors in the 1061 patients with positive RLNs.
Characteristic

 N

 OS

 PFS

 LRRFS

 DMFS
AHR (95% CI) a

 P-Value

 AHR (95% CI) a

 P-Value

 AHR (95% CI) a

 P-Value

 AHR (95% CI) a

 P-Value
N3 as reference

 232

 reference

reference

reference

reference

Other N1

 492

 0.27 (0.19-0.39)

 p<.001

 0.32 (0.24-0.42)

 p<.001

 0.48 (0.32-0.71)

 p<.001

 0.25 (0.18-0.36)

 p<.001
Other N2

 266

 0.38 (0.25-0.57)

 p<.001

 0.45 (0.33-0.60)

 p<.001

 0.59 (0.38-0.92)

 p=.019

 0.40 (0.27-0.57)

 p<.001
N1 with high-risk CLN ENE

 39

 0.77 (0.42-1.42)

 p=.402

 0.72 (0.43-1.19)

 p=.199

 0.63 (0.25-1.62)

 p=.339

 0.80 (0.45-1.41)

 p=.435
N2 with high-risk CLN ENE

 32

 0.68 (0.35-1.31)

 p=.247

 0.70 (0.41-1.19)

 p=.186

 0.78 (0.30-1.98)

 p=.595

 0.51 (0.24-1.06)

 p=.070