Incidence and patterns of retropharyngeal lymph node involvement in oropharyngeal carcinoma

Topohistology of the cranial nerves IX-XII at the cranial base and upper parapharyngeal space: A histological study using human fetuses

The topographical relationships among the lower cranial nerves, internal carotid artery (ICA), and internal jugular vein (IJV) in the upper parapharyngeal neurovascular bundle remain obscure. Thus, details of the anatomy were examined in human fetus histology. We observed the horizontal histological sections from 20 midterm (9-18 weeks) and 12 near-term (28-40 weeks) fetuses. At the external skull base, the glossopharyngeal nerve crosses the anterior aspect of the IJV to reach the medially located Hyrtl's fissure in the petrous temporal bone. The nerve crossed the anterior aspect of the ICA medially near or below the first cervical nerve root. Below the hypoglossal nerve canal, the accessory nerve crosses the anterior or posterior aspects of the IJV and moves laterally. During the half-spiral course, the hypoglossal nerve was tightly attached to the posterolateral-anterior aspects of the vagus nerve and surrounded by a common nerve sheath. The glossopharyngeal ganglia sometimes extended inferiorly to the level of the hypoglossal nerve canal but were absent along the inferior course. The inferior vagal ganglion rarely extends above the occipital condyle. The superior cervical sympathetic ganglion occasionally extends above the first cervical nerve root. The IJV (or ICA) descends to the lateral (or medial) margins of the parapharyngeal neurovascular bundle. The glossopharyngeal (or accessory) nerve crosses the ICA (or IJV) to exit the bundle at the base of the skull (or below the hypoglossal nerve canal). The glossopharyngeal and vagus inferior ganglia differ at each site.

Prevalence and risk factors for retropharyngeal and retro-styloid lymph node metastasis in hypopharyngeal carcinoma

BACKGROUND

We evaluated the prevalence and identified the risk factors for retropharyngeal and retro-styloid lymph node metastasis (LNM) in patients with hypopharyngeal carcinoma (HPC). This was achieved using a combination of magnetic resonance (MR) and [18 F]-fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET)/computed tomography (CT) images.

METHODS

Two board-certified radiation oncologists retrospectively reviewed pretreatment FDG-PET/CT images and contrast-enhanced thin-slice CT and MR images of 155 patients with HPC who underwent radiotherapy. Fisher's exact tests and logistic regression analyses were performed to assess the risk factors for LNM.

RESULTS

Retropharyngeal LNM (RPLNM) was confirmed in 20 (13%) patients. Posterior wall (PW) tumors (odds ratio [OR]: 4.128, 95% confidence interval [CI]: 1.339-12.727; p = 0.014) and bilateral or contralateral cervical LNM (OR: 11.577, 95% CI: 2.135-62.789; p = 0.005) were significantly correlated with RPLNM. The RPLNM was found in 9 (32%) of the 28 patients with PW tumors. Of these 9 patients, 2 (7%) had ipsilateral RPLNM, 3 (11%) had contralateral RPLNM, and 4 (14%) had bilateral RPLNM. The PW tumors were significantly associated with contralateral RPLNM (p < 0.001). Retro-styloid LNM (RSLNM) was confirmed in two (1%) patients, both of whom had ipsilateral RSLNM with lymph nodes (LNs) of ≥ 15 mm in the upper limit of ipsilateral level II. A significant association was found between LNs of ≥ 15 mm in the upper limit of ipsilateral level II and ipsilateral RSLNM (p = 0.001).

CONCLUSIONS

The RPLNM was identified in 13% of patients with HPC. The PW tumors and bilateral or contralateral cervical LNM were risk factors for RPLNM; particularly, PW tumors were a specific risk factor for contralateral RPLNM. Although the RSLNM was rare, LNs of ≥ 15 mm in the upper limit of ipsilateral level II were a risk factor for ipsilateral RSLNM.

Incidence and predictive factors of retropharyngeal lymph node metastases in patients with oropharyngeal cancer undergoing multimodality treatment planning imaging

BACKGROUND

We investigated the incidence and predictive factors of retropharyngeal lymph node (RPLN) metastases in patients with oropharyngeal cancer (OPC) undergoing multimodality treatment planning imaging before radiotherapy.

METHODS

Consecutive patients with OPC treated with curative-intent radiotherapy from 2017 to 2019 were retrospectively analyzed. Treatment planning comprised contrast-enhanced computed tomography (CT), magnetic resonance imaging (MRI), and fluorodeoxyglucose-positron emission tomography (FDG-PET) unless contraindicated.

RESULTS

Of 300 patients, 66 (22%) had radiological evidence of RPLN involvement on planning images, compared to 17 (6%) on diagnostic CT alone. On multivariate analysis, RPLN involvement was statistically (p < 0.05) associated with tonsil, soft palate, and posterior pharyngeal wall primaries, and with disease extension to the soft palate or vallecula.

CONCLUSIONS

Multimodality treatment planning imaging reveals a high rate of RPLN metastases from OPC compared to diagnostic CT alone. Patients with tonsil, soft palate, or posterior pharyngeal wall primaries or disease extending to the soft palate or vallecula appear at higher risk.

Prevalence and risk factors of retro-styloid lymph node metastasis in oropharyngeal carcinoma

BACKGROUND

Supporting data defining the selection criteria of level VIIb for inclusion in the target volume in radiotherapy (RT) planning are insufficient. We evaluated the prevalence of level VIIb retro-styloid lymph node metastasis (RSLNM) and associated risk factors in patients with oropharyngeal carcinoma (OPC).

MATERIALS AND METHODS

We retrospectively reviewed pre-treatment [¹⁸F]-fluoro-2-deoxy-d-glucose-positron emission tomography/computed tomography (CT) along with contrast-enhanced thin slice CT and magnetic resonance (MR) images of 137 patients pathologically confirmed as having OPC who underwent RT. The location of lymph nodes (LNs) was confirmed on the planning CT images. Fisher's exact test and logistic regression analyses were made to determine the risk factors of RSLNM.

RESULTS

RSLNM was confirmed in 18 (13%) patients. All RSLNMs were located within level VIIb on the planning CT images. No patients exhibited LNM in contralateral level VIIb. Furthermore, no patients with negative or single ipsilateral cervical LNM had RSLNM. Fisher's exact test revealed that smoking status (p=.027), multiple ipsilateral cervical LNM (p=.045) and LN ≥15 mm in the upper limit of ipsilateral level II (p<.001) were significantly associated with RSLNM. Logistic regression analyses revealed that the presence of LNs ≥15 mm in upper limit of ipsilateral level II was significantly associated with RSLNM (odds ratio: 977.297; 95% confidence interval: 57.629-16573.308; p<.001).

CONCLUSIONS

RSLNM is relatively common in patients with OPC with a prevalence rate of approximately 10%. The prevalence of RSLNM in patients with negative or single ipsilateral cervical LNM and contralateral RSLNM is extremely low; therefore, level VIIb can be excluded from the target volume in such patients. LN ≥15 mm in the upper limit of ipsilateral level II is a risk factor for RSLNM. Ipsilateral level VIIb should be included in the target volume for patients with this risk factor.KEY MESSAGERetro-styloid lymph node metastasis (RSLNM) prevalence is ∼10% in oropharyngeal carcinoma.Lymph node ≥15 mm in ipsilateral level II upper limit is a risk factor for RSLNM.

Prevalence and prognostic impact of retropharyngeal lymph nodes metastases in oropharyngeal squamous cell carcinoma: Meta-analysis of published literature

BACKGROUND

This systematic review and meta-analysis aims to estimate the prevalence and prognostic impact of retropharyngeal lymph node metastases (RLNMs) in oropharyngeal squamous cell carcinoma (OPSCC).

METHODS

This meta-analysis was conducted according to PRISMA guidelines.

INCLUSION CRITERIA

studies with more than 20 patients reporting the prevalence or prognostic impact of RLNMs in OPSCC. Whenever available, data on HPV status and subsites were extracted.

RESULTS

Twenty-two articles were included. The overall prevalence of RLNMs in OPSCC was 13%, with no significant differences depending on HPV status. The highest prevalence was observed for posterior pharyngeal wall SCC (24%), followed by soft palate (17%), palatine tonsil (15%), and base of tongue (8%). RLNMs were associated with a significantly higher risk of death (HR:2.54;IC95%1.89-3.41) and progression (HR:2.44;IC95%1.80-3.30).

CONCLUSIONS

The prevalence of RLNMs in OPSCC was 13%, being higher in tumors of the posterior pharyngeal wall. RLNMs were associated with unfavorable outcomes.

Novel Strategies for Managing Retropharyngeal Lymph Node Metastases in Head and Neck and Thyroid Cancer with Transoral Robotic Surgery (TORS)

Retropharyngeal metastases are encountered in a variety of head and neck malignancies, imposing significant surgical challenges owing to their distinct location and proximity to neurovascular structures. Radiotherapy is the recommended treatment in most cases owing to its oncological efficacy. However, retropharyngeal irradiation affects the superior pharyngeal constrictor muscles and parotid glands, with the potential for long-term dysphagia and xerostomia. A younger oropharyngeal and thyroid cancer patient demographic is trending, fueling interest in treatment de-escalation strategies. Consequently, reducing radiotoxicity and its long-term effects is of special relevance in modern head and neck oncology practice. Through its unique ability to safely extirpate these traditionally difficult-to-access retropharyngeal lymph nodes via a natural orifice, TransOral Robotic Surgery (TORS) can considerably lower the surgical morbidity of retropharyngeal lymph node dissection (RPLND), compared with current existing approaches. This review summarizes the latest developments in the field, exposing current research gaps and discusses specific clinical settings where TORS could enable treatment de-escalation. In early-stage node-negative oropharyngeal cancer, single-modality surgical treatment with TORS RPLND may improve risk stratification of metastasis and recurrence in this region. TORS RPLND is also a potentially viable treatment option in salvage of an isolated retropharyngeal node recurrence or in the primary setting of a thyroid malignancy with a single positive retropharyngeal node. In time, TORS RPLND may provide an alternative de-escalation strategy in these three scenarios. However, with the reported morbidities, further prospective trials with long-term follow-up data are required to prove oncological safety and functional benefits over existing strategies.

Radiologic criteria of retropharyngeal lymph node metastasis in maxillary sinus cancer

Objective

To determine the most appropriate radiologic criteria of metastatic retropharyngeal lymph nodes (RLNs) in patients with maxillary sinus cancer (MSC).

Materials and methods

We retrospectively evaluated 16 consecutive patients who underwent magnetic resonance imaging (MRI) before and after the treatment of locally advanced squamous cell carcinoma of the maxillary sinus. The minimal and maximal diameters of all RLNS were recorded. RLNs were classified as metastatic on the basis of the MRI follow-up (f/u). RLNs were considered non-metastatic if stable disease continued until the final MRI f/u and metastatic in cases with different evaluations (complete response, partial response, progressive disease) determined using Response Evaluation Criteria in Solid Tumours (RECIST) ver. 1.1. The receiver operating characteristic curve (ROC) and area under the curve (AUC) were used to assess the accuracy of various criteria in the diagnosis of metastatic RLNs.

Results

Of the 34 RLNs in 16 cases observed on pretreatment MRI, 7 were classified as metastatic RLNs and 27 as non-metastatic RLNs. Using the radiologic criteria, metastatic RLNs tended to be diagnosed more accurately with the minimal axial diameter than with the maximal axial diameter (AUC; 0.97 vs. 0.73, p = 0.06). The most accurate size criterion of metastatic RLNs was a minimal axial diameter of 5 mm or larger, with an accuracy of 94.1% (32 of 34).

Conclusions

The most appropriate radiologic criterion of metastatic RLNs in MSC is a minimal axial diameter of 5 mm or longer.

Retropharyngeal Lymph Node Metastasis Diagnosed by Magnetic Resonance Imaging in Hypopharyngeal Carcinoma: A Retrospective Analysis From Chinese Multi-Center Data

Background

To assess the prevalence, risk factors and prognostic significance of retropharyngeal lymph node (RPLN) metastasis diagnosed by magnetic resonance imaging (MRI) in patients with hypopharyngeal squamous cell carcinoma (HPSCC).

Methods

259 patients from three cancer institutions in China from Jan 2010 to Dec 2018 were analyzed, retrospectively. All the patients had been given pre-treatment magnetic resonance imaging (MRI) of head and neck and were then treated with definitive radiotherapy with or without chemotherapy. Pretreatment diagnostic MRIs were reviewed by a dedicated head and neck radiologist, for the presence or absence of radiographically positive RPLN, cervical LN and tumor invasion.Demographic variables were analysed by descriptive statistics using SPSS 20.0. Predictors of the presence of RPLN and its prognostic significance were examined.

Results

RPLN metastasis was discovered in 44 patients (17%). Logistic analysis showed that posterior pharyngeal wall (PPW) primary tumor; PPW invasion; N2-3; multiple cervical lymph node (LN) involvement (>2 LNs) were associated with RPLN metastasis, with metastasis rates 37%, 30%, 31% and 33% respectively. Patients with RPLN metastasis had a significantly reduced 5-year overall survival (OS) and disease-free survival (DFS) compared to the non-RPLN metastasis group (OS 28% vs. 48%, p=0.001; DFS 25% vs. 41%, p=0.040).

Conclusions

RPLN metastasis was not uncommon in HPSCC patients. Risk factors were: PPW primary tumor, PPW invasion and cervical LN status. RPLN metastasis is a poor prognosticator for survival.

Prevalence and distribution of cervical lymph node metastases in HPV-positive and HPV-negative oropharyngeal squamous cell carcinoma

OBJECTIVE

In oropharyngeal squamous cell carcinoma (OP-SCC), the prevalence and distribution of clinical and pathological lymph node metastasis in the neck have been extensively reported. It served as the basis for consensus recommendations on the selection of the lymph node levels in the neck requiring a treatment. The objective of the study is to compare the prevalence and distribution of neck node metastases in HPV+ and HPV- OP-SCC from a large series of patients with OP-SCC who underwent a cervical lymph-node dissection (LND) as part of their treatment.

METHODS

The study concentrated on OP-SCC patients treated by various neck node dissection (LND) procedures from January 2014 to December 2018 in 3 French institutions. Patients with prior head and neck cancer, prior neck surgery, the use of induction chemotherapy, or patients with carcinoma of unknown primary were excluded. HPV-status was assessed by p16 immunohistochemistry. For each patient, the clinical and the pathological nodal status, as well as the distribution of the positive nodes in each neck level (from Ia to V) were reported.

RESULTS

Two-hundred and sixty-three patients were included (126 p16-negative (p16-), and 137 p16-positive (p16+). The rate of clinical positive node (cN+) reached 54% and 88.3% in the p16- and p16+ groups, respectively (p < 0.001); the corresponding rate of pathological positive node (pN+) reached 61.9% and 91.2%, respectively (p < 0.001). Regarding the clinical lymph node distribution, in p16+ patients, more positive nodes were observed in the ipsilateral level IV (p = 0.003), and less positive nodes were observed in the contralateral levels III and IV (p = 0.003 and p = 0.045, respectively). Regarding the pathologic lymph node distribution in the ipsilateral neck, in the cN0 patients, no significant difference was observed between p16- and p16+ patients (p = 0.33 to 1); in the cN+ patients, the nodes were distributed in levels Ib, II, III, IV and V without differences between the p16- and the p16+ patients. In the contralateral neck of p16- patients, nodes metastases were mainly observed in levels II, III and IV, whereas for the p16+ patients, positive nodes were only observed in level II (p = 0.03).

CONCLUSION

This study demonstrated the higher prevalence of cN+ and pN+ in p16+ OP-SCC patients, but without meaningful difference in the distribution of the lymph node drainage between p16- and p16+ OP-SCC. It indicates that no difference should be made between p16- and p16+ patients regarding the extend of neck treatment.

Is the retropharyngeal lymph node the first echelon node for carcinoma tonsil? Prospective evaluation and literature review

PURPOSE

Tonsil cancer being predominantly treated by non-surgical means, there is a paucity of data on lymph nodal drainage pathways and histo-pathologically confirmed metastatic rates. This study assesses the retropharyngeal lymph node (RPLN) in N0 squamous cell carcinoma tonsil as a possible first echelon node and a site for occult metastasis.

METHODS

Prospective study involving treatment naïve N0 carcinoma tonsil treated by primary surgery and adjuvant treatment from June 2017 to March 2019. In-vivo lymph nodal drainage patterns were assessed by sentinel node mapping by preoperative SPECT-CT and intra-operative hand-held Gamma probe. All patients had a subsequent Level I-III/IV sampling neck dissection supplemented with RPLN dissection. Histological evaluation of sentinel nodes and RPLN involved step-serial sectioning and pan-cytokeratin immunohistochemistry. A comprehensive literature review was performed with keywords "retropharyngeal lymph node", "oropharynx", "tonsil", "squamous cell carcinoma" to determine the incidence of RPLN positivity in previously published series.

RESULTS

Sentinel node was successfully identified by SPECT-CT in all 17 patients (ipsilateral level 2a-13/17, 2b-1/17, 3-1/17; bilateral 2a-1/17; isolated contralateral retropharyngeal node-1/17). 8/17 had occult neck metastasis. In no patient was an ipsilateral RPLN identified as the sentinel node. Histological sampling did not indicate metastatic tumor in the RPLN in any patient (0/17). A systematic literature review further confirmed that RPLN metastasis in oropharyngeal cancer is noted only in the presence of pN + disease at other neck levels, and isolated RPLN metastasis is extremely rare (1.2%).

CONCLUSION

The ipsilateral RPLN is not identified either as the first echelon node or as a site of occult metastatic disease in N0 tonsil cancer.

CTRI REGISTRATION

CTRI/2019/06/019551.

Radiotherapy for Oropharyngeal Carcinoma With an Uninvolved Contralateral Neck: The Safety of Omission of Contralateral High Level II and Retropharyngeal Lymph Nodes From Elective Target Volumes

AIMS

To analyse outcomes and patterns of failure in patients with oropharyngeal carcinoma (OPC) treated with definitive volumetric modulated arc therapy with omission of contralateral high level II lymph nodes (HLII) and retropharyngeal lymph nodes (RPLN) in the contralateral uninvolved neck.

MATERIALS AND METHODS

Patients with OPC treated between January 2016 and July 2019 were retrospectively identified. In the absence of contralateral neck disease, institutional protocols allowed omission of contralateral HLII and contralateral RPLN in the additional absence of ipsilateral RPLN, soft palate/posterior pharyngeal wall primary.

RESULTS

In total, 238 patients with OPC and an uninvolved contralateral neck received definitive (chemo)radiotherapy with bilateral neck treatment. The median follow-up was 30.6 months. Two-year local control, regional control and overall survival were 91.0, 91.6 and 86.5%, respectively. Contralateral HLII were omitted in 159/238 (66.8%) patients; this included 106 patients in whom the primary tumour was at/crossed the midline. The contralateral RPLN region was omitted from elective target volumes for 175/238 (73.5%); this included 114 patients with a primary tumour at/crossed the midline. The mean contralateral parotid dose when contralateral HLII and RPLN were both omitted was 24.4 Gy, compared with 28.3 Gy without HLII/RPLN omission (P < 0.001). Regional progression occurred in 18/238 (7.6%) patients, all involving the ipsilateral neck with one bilateral. There were no recurrences in the contralateral HLII or RPLN regions.

CONCLUSION

In patients with OPC and an uninvolved contralateral neck receiving bilateral (chemo)radiotherapy, the omission of contralateral RPLN and HLII from elective target volumes was safe and could lead to reduced contralateral parotid doses.

Retropharyngeal Lymph Node Involvement in Oropharyngeal Carcinoma: Impact upon Risk of Distant Metastases and Survival Outcomes

The influence of retropharyngeal lymph node (RPLN) involvement on prognosis in oropharyngeal carcinoma remains poorly defined. The aim of this study was to assess the impact of RPLN involvement upon outcomes. A single-centre retrospective analysis of 402 patients with oropharyngeal carcinoma treated nonsurgically between 2010 and 2017 was performed. All had a baseline 2-[fluorine-18]-fluoro-2-deoxy-d-glucose (FDG) PET-CT and contrast-enhanced MRI and/or CT. RPLN status was determined by radiology review of cases with reported abnormal RPLN. Multivariate backwards logistic regression was used to examine impact on outcomes of factors. Abnormal RPLNs were identified in 40/402 (10%) of patients. Median follow up was 42.9 months. RPLN involvement was associated with inferior 3 year outcomes for overall survival (OS) (67.1% vs. 79.1%, p = 0.006) and distant metastases-free survival (DMFS) (73.9% versus 88.0%, p = 0.011), with no significant difference in local control (81.6% vs. 87.7%, p = 0.154) or regional control (80.7% vs. 85.4%, p = 0.252). On multivariate analysis abnormal RPLN, no concurrent chemotherapy and ongoing smoking were associated with inferior DMFS and OS, while advanced T stage was also associated with inferior OS. In summary, RPLN involvement, present in 10% of patients, was an independent prognostic factor for the development of distant disease failure translating into inferior OS. These findings need confirmation in future studies.