A complete magnetic sentinel lymph node biopsy procedure in oral cancer patients: A pilot study

Step Serial Sectioning in Head and Neck Squamous Cell Carcinoma of Unknown Primary

Importance

Patients with suspected head and neck squamous cell carcinoma of unknown primary (HNSCCUP) may undergo tonsillectomy and tongue base mucosectomy (TBM) to help identify clinicoradiologically occult primary disease. It is hypothesized that when these diagnostic specimens are analyzed, conventional histopathological (CH) techniques risk missing small primary tumors that may be hidden in the tissue blocks.

Objective

To establish the outcomes of a step serial sectioning (SSS) histopathological technique vs CH when analyzing diagnostic tissue specimens from TBM and tonsillectomy performed for HNSCCUP.

Design, Setting, and Participants

The MOSES prospective multicenter noninterventional cohort study was conducted over a 25-month period from November 2019 at secondary and tertiary care ear, nose, and throat departments in the United Kingdom and included adults with clinicoradiologically occult HNSCCUP who were undergoing TBM.

Intervention

Conventional histopathological techniques performed on TBM and tonsillectomy specimens at participating centers, followed by SSS performed at the central laboratory.

Main Outcome

Identification of cancer on central histopathological review of TBM and tonsillectomy specimens.

Results

Tissue from 58 eligible patients was analyzed (median [range] age, 58 [47-82] years; 10 women [17%]), with 20 480 sections cut in the laboratory and 4096 sections directly examined by a pathologist (median [range], 64 [28-135] per patient). The overall identification rate for TBM following SSS according to study protocol was 50.0% (95% CI, 37.5%-62.5%) and by subgroups was 42.9% (95% CI, 21.4%-67.4%) when performed following a negative bilateral tonsillectomy, 46.7% (95% CI, 24.8%-69.9%) at the same time as bilateral tonsillectomy, and 57.1% (95% CI, 36.5%-75.5%) following historic tonsillectomy. Conventional histopathological techniques at central review identified 2 undiagnosed primary tumors and revised the diagnosis of 2 other cases (1 nonmalignant and another down staged). Step serial sectioning identified a single additional tumor: an ipsilateral synchronous tongue base tumor for which a contralateral tumor had been identified on CH. Multifocal disease was seen in 5 (8.6%); all were human papillomavirus-related and in the tongue base.

Conclusions and Relevance

In this multicenter cohort study of patients undergoing TBM for HNSCCUP, SSS was associated with added considerable histopathological workload with minimal additional diagnostic benefit. A second opinion for conventional histological techniques may be more beneficial. Synchronous primary disease should be considered when planning diagnostic oropharyngeal surgery for these patients.

Performance of a Nonlinear Magnetic Handheld Probe for Intraoperative Sentinel Lymph Node Detection: A Phantom Study

OBJECTIVE

This study investigates the performance of the DiffMag handheld probe (nonlinear magnetometry), to be used for sentinel lymph node detection. Furthermore, the performance of DiffMag is compared with a gamma probe and a first-order magnetometer (Sentimag®, linear magnetometry).

METHODS

The performance of all three probes was evaluated based on longitudinal distance, transverse distance, and resolving power for two tracer volumes. A phantom was developed to investigate the performance of the probes for a clinically relevant situation in the floor of the mouth (FOM).

RESULTS

Considering the longitudinal distance, both DiffMag handheld and Sentimag® probe had comparable performance, while the gamma probe was able to detect at least a factor of 10 deeper. Transverse distances of 13, 11, and 51 mm were measured for the small tracer volume by the DiffMag handheld, Sentimag®, and the gamma probe, respectively. For the large tracer volume this was 21, 18, and 55 mm, respectively. The full width at half maximum, at 7 mm probe height from the phantom surface, was 14, 12, and 18 mm for the small tracer volume and 15, 18, and 25 mm for the large tracer volume with the DiffMag handheld, Sentimag®, and gamma probe, respectively.

CONCLUSIONS

With a high resolving power but limited longitudinal distance, the DiffMag handheld probe seems suitable for detecting SLNs which are in close proximity to the primary tumor. In this study, comparable results were shown using linear magnetometry. The gamma probe reached 10 times deeper, but has a lower resolving power compared with the DiffMag handheld probe.

Diagnostic accuracy of combined optical- and radio-guided SNB for neck staging of oral squamous cell carcinoma lesions in the anterior oral cavity

PURPOSE

The purpose was to investigate the diagnostic performance of bimodal optical and radio-guided sentinel node biopsy (SNB) for oral squamous cell carcinoma (OSCC) sub-sites in the anterior oral cavity.

METHODS

Prospective study of 50 consecutive patients with cN0 OSCC scheduled for SNB was injected with the tracer complex Tc99m:ICG:Nacocoll. A near-infrared camera was applied for optical SN detection. Endpoints were modality for intraoperative SN detection and false omission rate at follow-up.

RESULTS

In all patients, a SN could be detected. In 12/50 (24%) of cases, the SPECT/CT showed no focus in level 1, but intraoperatively a SN in level 1 was optically detected. In 22/50 cases (44%), an additional SN was identified only due to the optical imaging. At follow-up, the false omission rate was 0%.

CONCLUSION

Optical imaging appears to be an effective tool to allow real-time SN identification comprising level 1 unaffected by possible interference of radiation site from the injection.

Tuning Excitation Field Frequency for Magnetic Particle Sensing using Superparamagnetic Quantifier

Nonlinear handheld detection of magnetic nanoparticles is used to assess the lymph node status of cancer patients. Joint sensitivity and resolving power of nonlinear handheld detection can be maximized by optimizing the frequency of the excitation field, which is strongly influenced by Brownian and Néel relaxation. The characteristic frequency of magnetic nanoparticles that defines sensitivity and resolving power is usually assessed by AC susceptometry. In this study, we used SPaQ data to predict handheld detection performance for magnetic nanoparticles with various particle sizes. SPaQ assesses dynamics by measuring the derivative of the magnetization originating from magnetic nanoparticles activated by an alternating excitation field. The ratio between the maximum signal difference and full-width-at-half-maximumis used to estimate the optimal excitation frequency. Thereupon, it was shown that a particle with a combination of Brownian and Néel relaxation is superior in nonlinear handheld detection compared to Brownian or Néel only particles. Moreover, the optimal excitation frequency is generally established at a slightly higher frequency compared to the characteristic frequency assessed by AC susceptometry. Consequently, this insight into the consequences of the dynamic behavior of magnetic nanoparticles under an alternating magnetic field enables the optimization of nonlinear handheld detection for specific clinical applications.

Target Definition in MR-Guided Adaptive Radiotherapy for Head and Neck Cancer

Simple Summary

Adaptive radiotherapy for head and neck cancer has become more routine due to an increase in imaging quality and improvement in radiation techniques. With the availability of faster adaptive workflows, it is possible to adapt more easily to (daily) changes. MRI offers besides great anatomical imaging, also functional information about the tumor and surrounding tissue. The aim of this review is to provide current state of evidence about target definition on MRI for adaptive strategies in the treatment of head and neck cancer.

Abstract

In recent years, MRI-guided radiotherapy (MRgRT) has taken an increasingly important position in image-guided radiotherapy (IGRT). Magnetic resonance imaging (MRI) offers superior soft tissue contrast in anatomical imaging compared to computed tomography (CT), but also provides functional and dynamic information with selected sequences. Due to these benefits, in current clinical practice, MRI is already used for target delineation and response assessment in patients with head and neck squamous cell carcinoma (HNSCC). Because of the close proximity of target areas and radiosensitive organs at risk (OARs) during HNSCC treatment, MRgRT could provide a more accurate treatment in which OARs receive less radiation dose. With the introduction of several new radiotherapy techniques (i.e., adaptive MRgRT, proton therapy, adaptive cone beam computed tomography (CBCT) RT, (daily) adaptive radiotherapy ensures radiation dose is accurately delivered to the target areas. With the integration of a daily adaptive workflow, interfraction changes have become visible, which allows regular and fast adaptation of target areas. In proton therapy, adaptation is even more important in order to obtain high quality dosimetry, due to its susceptibility for density differences in relation to the range uncertainty of the protons. The question is which adaptations during radiotherapy treatment are oncology safe and at the same time provide better sparing of OARs. For an optimal use of all these new tools there is an urgent need for an update of the target definitions in case of adaptive treatment for HNSCC. This review will provide current state of evidence regarding adaptive target definition using MR during radiotherapy for HNSCC. Additionally, future perspectives for adaptive MR-guided radiotherapy will be discussed.

A Comprehensive Grading System for a Magnetic Sentinel Lymph Node Biopsy Procedure in Head and Neck Cancer Patients

Simple Summary

With 30% of clinically negative early-stage oral cancer patients harboring occult metastasis, an accurate staging of metastatic lymph nodes (LN) is of utmost importance for treatment planning. A magnetic sentinel lymph node biopsy (SLNB) procedure is offered as an alternative to conventional SLNB in oral oncology, however, a grading system is missing. A proper grading system is preferred to connect the different components of the magnetic SLNB: preoperative imaging, intraoperative detection, and histopathological examination of sentinel lymph nodes (SLNs). This study aims to provide a first grading system based on the distribution of a magnetic tracer, by means of preoperative magnetic resonance imaging (MRI), intraoperative estimation of iron content, and histopathological assessment of resected nodes. Pre- and post-operative MRI and harvested SLNs of eight tongue cancer patients with successful magnetic SLNB procedure were used for analyses.

Abstract

A magnetic sentinel lymph node biopsy ((SLN)B) procedure has recently been shown feasible in oral cancer patients. However, a grading system is absent for proper identification and classification, and thus for clinical reporting. Based on data from eight complete magnetic SLNB procedures, we propose a provisional grading system. This grading system includes: (1) a qualitative five-point grading scale for MRI evaluation to describe iron uptake by LNs; (2) an ex vivo count of resected SLN with a magnetic probe to quantify iron amount; and (3) a qualitative five-point grading scale for histopathologic examination of excised magnetic SLNs. Most SLNs with iron uptake were identified and detected in level II. In this level, most variance in grading was seen for MRI and histopathology; MRI and medullar sinus were especially highly graded, and cortical sinus was mainly low graded. On average 82 ± 58 µg iron accumulated in harvested SLNs, and there were no significant differences in injected tracer dose (22.4 mg or 11.2 mg iron). In conclusion, a first step was taken in defining a comprehensive grading system to gain more insight into the lymphatic draining system during a magnetic SLNB procedure.

Sentinel lymph node biopsy with a handheld cordless magnetic probe following preoperative MR lymphography using superparamagnetic iron oxide for clinically N0 early oral cancer: A feasibility study

PURPOSE

Radioisotope (RI) tracers are generally used for preoperative mapping of sentinel lymph node (SLN) and intraoperative detection with a portable γ probe. However, the use of RI has several limitations. Therefore, a method without RI is required for the widespread application of SLN biopsy. The purpose of this study was to evaluate the feasibility of SLN biopsy with a handheld cordless magnetic probe following magnetic resonance lymphography (MRL) using superparamagnetic iron oxide (SPIO) and for clinically N0 early oral cancer.

MATERIALS AND METHODS

MRL using SPIO and SLNB with the handheld cordless magnetic probe were performed for 27 patients with clinically N0 early oral cancer.

RESULTS

In all 27 patients (100%), SLNs were detected by MRL, and the total and mean number of SLNs were 73 and 2.7, respectively. All SLNs identified by MRL were detectable using the magnetic probe in all patients.

CONCLUSIONS

SLNB with handheld cordless magnetic probe following preoperative SLN mapping by MRL using SPIO is feasible, without RI use, for neck management in cases of clinically N0 early oral cancer.

The neuropeptide calcitonin gene-related peptide links perineural invasion with lymph node metastasis in oral squamous cell carcinoma

Objective

Although perineural invasion (PNI) is well-known to be correlated with and able to predict lymph node metastasis (LNM) in oral squamous cell carcinoma (OSCC), the clinical and molecular correlation between PNI and LNM has not been elucidated, and preoperative biomarkers for LNM prediction in OSCC are urgently needed.

Materials and methods

The correlation between PNI and LNM was retrospectively evaluated using a cohort of 218 patients diagnosed with OSCC. Candidate neuropeptides were screened based on TCGA database and verified via immunohistochemistry and Western blot analyses. ELISA was used to detect calcitonin gene-related peptide (CGRP) in patient plasma. In vitro assays were used to explore the effects of CGRP on OSCC cells.

Results

OSCC patients with PNI had a higher incidence of LNM (69.86% vs. 26.2%, P < 0.0001, n = 218). CGRP expression was upregulated in the PNI niche and in metastatic lymph nodes, and was correlated with poor overall survival of OSCC patients. Preoperative plasma CGRP levels were higher in OSCC patients (n = 70) compared to healthy donors (n = 60) (48.59 vs. 14.58 pg/ml, P < 0.0001), and were correlated with LNM (P < 0.0001) and PNI (P = 0.0002). Preoperative plasma CGRP levels alone yielded an AUC value of 0.8088 to predict LNM, and CGRP levels combined with preoperative T stage reached an AUC value of 0.8590. CGRP promoted proliferation and migration abilities of OSCC cells, which could be antagonized by either pharmacological or genetic blockade of the CGRP receptor.

Conclusions

The neuropeptide CGRP links PNI and LNM in OSCC, and preoperative plasma CGRP levels can be used to predict LNM in OSCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08998-9.