Recommendation regarding the cranial upper border of level IIb in delineating clinical target volumes (CTV) for nasopharyngeal carcinoma

Lijun Wang,Yatian Liu,Shengfu Huang,Lanfang Zhang,Xia He

doi:10.1186/s13014-020-01720-2

Lijun Wang, Yatian Liu + Show 3 more

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https://doi.org/10.1186/s13014-020-01720-2

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Abstract

PurposeTo recommend a cranial border for level IIb in delineating clinical target volumes (CTV) for nasopharyngeal carcinoma (NPC) patients receiving intensity-modulated radiotherapy and to help reach a consensus on contouring level IIb in CTV.MethodsFrom 2012 to 2016, 331 nonmetastatic NPC patients treated with IMRT were retrospectively enrolled. Based on the AJCC 8th staging system of NPC, there were 15 stage I, 76 stage II, 103 stage III, and 137 stage IV patients. The distribution of cervical lymph nodes in NPC was assessed based on imaging. Comparisons of the safety and parotid dose parameters between patients with and without a reduction in the size of level IIb were conducted using SPSS 25.0 and R 2.14.2 software.ResultsMetastasis rates in the most commonly involved lymph nodes, the lateral retropharyngeal and IIb nodes, were 82.8% and 64.0%, respectively. Among patients with level IIb involvement, the upper borders of the metastatic nodes were beyond the caudal edge of C1 in 13.7% of cases. The parotid gland D50 and V26 values were significantly reduced after modifying the upper bound of level IIb used to delineate the CTV (P = 0.000).ConclusionIn principle, the upper bound of level IIb should reach the lateral skull base during delineation of the cervical CTV for NPC. To protect the parotid glands, however, individualized reduction of the upper bound of level IIb is recommended for patients who meet certain criteria.

Highlights

Compared to other head and neck squamous cell carcinomas, nasopharyngeal carcinoma (NPC) has a distinct epidemiology, etiology, and clinical manifestation [1]
Distribution of nodal in perch of level II Of the 212 patients with level IIb node involvement, the upper border of the metastatic lymph nodes relative to the cervical vertebra was assessed
It was found that the upper border in 58.02% (123/212) of the patients was reaching the cephalic edge of the second cervical vertebra (C2), it exceeded the caudal edge of the lateral process of the first vertebra (C1), the suggested upper border of level II in the 2013 updated international consensus guidelines, in 13.2% (28/212), and it reached the skull base in 2.83% (6/212) (Fig. 1)

Summary

Introduction

Compared to other head and neck squamous cell carcinomas, nasopharyngeal carcinoma (NPC) has a distinct epidemiology, etiology, and clinical manifestation [1]. Since NPC has the highest incidence of regional lymph node metastasis among head and neck cancers (HNC), these guidelines were primarily derived from patients with head and neck squamous cell carcinomas. Given the unique biological behavior of NPC, there is still controversy surrounding the delineation of the neck CTV for NPC. In an attempt to define more suitable cranial. Wang et al Radiat Oncol (2020) 15:270 boundaries for level IIb in neck CTV for NPC, we conducted this retrospective study and investigated the distribution of and rate of metastasis in high-seated lymph nodes in level IIb

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