Sentinel lymph node biopsy in oral and oropharyngeal squamous cell carcinoma: current status and unresolved challenges

Sentinel lymph node detection in thyroid carcinoma using [68Ga]Ga-tilmanocept PET/CT: a proof-of-concept study

PURPOSE

Sentinel lymph node (SLN) biopsy is rarely used for thyroid carcinoma staging. This is due to challenges associated with conventional Tc-99m-labeled tracers, often producing a large hotspot at the injection site, potentially hiding nearby SLNs (shine-through effect). The aim of this study was to demonstrate the feasibility and effectiveness of SLN visualization using the new PET tracer [68Ga]Ga-tilmanocept.

METHODS

Patients with thyroid carcinoma underwent ultrasound-guided peritumoral injection of [68Ga]Ga-tilmanocept and ICG-[99mTc]Tc-nanocolloid. [68Ga]Ga-tilmanocept PET/CT scans were conducted at 15 min and 60 min post-injection to visualize the SLNs. SLN biopsy was performed using ICG-[99mTc]TC-nanocolloid for intraoperative identification. The corresponding lymph node level was resected for reference.

RESULTS

Seven differentiated thyroid carcinoma (DTC) and 3 medullary thyroid carcinoma (MTC) patients were included, of which 6 were clinically node-negative. The median number of SLNs detected on [68Ga]Ga-tilmanocept PET/CT and resected was 3 (range 1-4) and 3 (range 1-5), respectively. Eight SLNs were found on PET/CT in the central compartment and 19 in the lateral compartment. The SLN procedure detected (micro)metastases in all patients except one. Seventeen of 27 pathologically assessed SLNs were positive, 8 negative, and 2 did not contain lymph node tissue, which led to upstaging in 5 out of 6 clinically node-negative patients.

CONCLUSIONS

[68Ga]Ga-tilmanocept PET/CT identified SLNs in all patients, mainly in the lateral neck. The SLNs were successfully surgically detected and resected using ICG-[99mTc]Tc-nanocolloid. This technique has the potential to improve neck staging, enabling more personalized treatment of thyroid cancer according to the lymph node status.

TRIAL REGISTRATION

2021-002470-42 (EudraCT).

Diagnostic Accuracy of Up-Front PET/CT and MRI for Detecting Cervical Lymph Node Metastases in T1-T2 Oral Cavity Cancer-A Prospective Cohort Study

The diagnostic accuracy of up-front 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) for detecting cervical lymph node metastases in patients with T1-T2 oral squamous cell carcinoma is reported with large discrepancies across the literature. We investigated the sensitivity, specificity, positive and negative predictive value, and accuracy of up-front PET/CT for detecting cervical lymph node metastases in this patient group and compared the performance to magnetic resonance imaging (MRI). In this prospective cohort study, 76 patients with T1-T2 oral squamous cell carcinoma underwent an up-front PET/CT and MRI at the Odense University Hospital from September 2013 to February 2016. Sentinel node biopsy and elective neck dissection were used for histopathological verification of the imaging modalities. Up-front PET/CT was significantly more sensitive than neck MRI (74% vs. 27%, p = 0.0001), but less specific (60% vs. 88%, p = 0.001). The accuracy of PET/CT and neck MRI was comparable (66% vs. 63%, p = 0.85), the PPV was slightly in favor of neck MRI (56% vs. 62%, p = 0.73), the NPV was slightly in favor of PET/CT (77% vs. 63%, p = 0.16). Neither PET/CT nor neck MRI should stand alone for N-staging T1-T2 oral cavity cancer.

Sentinel lymph node detection in thyroid carcinoma using 68Ga-tilmanocept PET/CT: a proof-of-concept study protocol

Sentinel lymph node biopsy (SLNB) is a diagnostic staging procedure. The procedure aims to identify the first draining lymph node(s), which are most likely to contain metastases. SLNB is applied in various cancers, but not currently in thyroid carcinoma. However, treatment strategies are changing, making SLNB clinically relevant. SLNB may lead to more accurate staging, prevent unnecessary treatment and help achieve earlier curation. 68Ga-tilmanocept PET/computed tomography (CT) can better localize sentinel lymph nodes (SLNs) near the primary tumor than planar scintigraphy and single-photon emission computed tomography (SPECT)/CT. This paper describes the rationale and design of a study investigating SLNB using 68Ga-tilmanocept PET/CT and indocyanine-green-99mTc-nanocolloid in ten differentiated and medullary thyroid carcinoma patients. Localization and number of SLNs, pathology result, optimal scan protocol, surgical time and surgeon's experience are examined. Clinical Trial Registration: 2021-002470-42 (EudraCT).

Preclinical evaluation of a mannose-labeled magnetic tracer for enhanced sentinel lymph node retention in the head and neck

Sentinel lymph node biopsy in cancers of the head and neck offers demonstrated clinical and diagnostic value, but adoption is limited by concerns about the detrimental consequence to survival of false negative results in a highly curable setting. The aim of this study was to demonstrate potential to overcome this via application of a novel mannose-labeled magnetic iron oxide tracer. In a large animal model, preoperative imaging and intraoperative magnetometer detection were used to identify magnetic lymph nodes. Iron quantification mapped the distribution of tracer within lymphatic levels. Over a 4-week test period, uptake of magnetic tracer in lymph nodes increased in a linear-like fashion, with a substantial percentage of accumulated iron (83%) being retained in the sentinel node. This result indicates a high affinity of mannose-labeled particles to the sentinel node, while providing a means for the magnetometer probe to indicate node status based on intraoperative signal.

What is the role of sentinel lymph node biopsy in the management of oral cancer in 2020?

Approximately 70–80% of patients with cT1-2N0 oral squamous cell carcinoma (OSCC) ultimately prove to have no cancer in the cervical lymphatics on final pathology after selective neck dissection. As a result, sentinel lymph node biopsy (SLNB) has been adopted during the last decade as a diagnostic staging method to intelligently identify patients who would benefit from formal selective lymphadenectomy or neck irradiation. While not yet universally accepted, SLNB is now incorporated in many national guidelines. SLNB offers a less invasive alternative to elective neck dissection (END), and has some advantages and disadvantages. SLNB can assess the individual drainage pattern and, with step serial sectioning and immunohistochemistry (IHC), can enable the accurate detection of micrometastases and isolated tumor cells (ITCs). Staging of the neck is improved relative to END with routine histopathological examination. The improvements in staging are particularly notable for the contralateral neck and the pretreated neck. However, for floor of mouth (FOM) tumors, occult metastases are frequently missed by SLNB due to the proximity of activity from the primary site to the lymphatics (the shine through phenomenon). For FOM cancers, it is advised to perform either elective neck dissection or superselective neck dissection of the preglandular triangle of level I. New tracers and techniques under development may improve the diagnostic accuracy of SLNB for early-stage OSCC, particularly for FOM tumors. Treatment of the neck (either neck dissection or radiotherapy), although limited to levels I–IV, remains mandatory for any positive category of metastasis (macrometastasis, micrometastasis, or ITCs). Recently, the updated EANM practical guidelines for SLN localization in OSCC and the surgical consensus guidelines on SLNB in patients with OSCC were published. In this review, the current evidence and results of SLNB in early OSCC are presented.

New Developments in Imaging for Sentinel Lymph Node Biopsy in Early-Stage Oral Cavity Squamous Cell Carcinoma

Sentinel lymph node biopsy (SLNB) is a diagnostic staging procedure that aims to identify the first draining lymph node(s) from the primary tumor, the sentinel lymph nodes (SLN), as their histopathological status reflects the histopathological status of the rest of the nodal basin. The routine SLNB procedure consists of peritumoral injections with a technetium-99m [^99mTc]-labelled radiotracer followed by lymphoscintigraphy and SPECT-CT imaging. Based on these imaging results, the identified SLNs are marked for surgical extirpation and are subjected to histopathological assessment. The routine SLNB procedure has proven to reliably stage the clinically negative neck in early-stage oral squamous cell carcinoma (OSCC). However, an infamous limitation arises in situations where SLNs are located in close vicinity of the tracer injection site. In these cases, the hotspot of the injection site can hide adjacent SLNs and hamper the discrimination between tracer injection site and SLNs (shine-through phenomenon). Therefore, technical developments are needed to bring the diagnostic accuracy of SLNB for early-stage OSCC to a higher level. This review evaluates novel SLNB imaging techniques for early-stage OSCC: MR lymphography, CT lymphography, PET lymphoscintigraphy and contrast-enhanced lymphosonography. Furthermore, their reported diagnostic accuracy is described and their relative merits, disadvantages and potential applications are outlined.

A DROP-IN beta probe for robot-assisted 68Ga-PSMA radioguided surgery: first ex vivo technology evaluation using prostate cancer specimens

BACKGROUND

Recently, a flexible DROP-IN gamma-probe was introduced for robot-assisted radioguided surgery, using traditional low-energy SPECT-isotopes. In parallel, a novel approach to achieve sensitive radioguidance using beta-emitting PET isotopes has been proposed. Integration of these two concepts would allow to exploit the use of PET tracers during robot-assisted tumor-receptor-targeted. In this study, we have engineered and validated the performance of a novel DROP-IN beta particle (DROP-INβ) detector.

METHODS

Seven prostate cancer patients with PSMA-PET positive tumors received an additional intraoperative injection of ~ 70 MBq 68Ga-PSMA-11, followed by robot-assisted prostatectomy and extended pelvic lymph node dissection. The surgical specimens from these procedures were used to validate the performance of our DROP-INβ probe prototype, which merged a scintillating detector with a housing optimized for a 12-mm trocar and prograsp instruments.

RESULTS

After optimization of the detector and probe housing via Monte Carlo simulations, the resulting DROP-INβ probe prototype was tested in a robotic setting. In the ex vivo setting, the probe-positioned by the robot-was able to identify 68Ga-PSMA-11 containing hot-spots in the surgical specimens: signal-to-background (S/B) was > 5 when pathology confirmed that the tumor was located < 1 mm below the specimen surface. 68Ga-PSMA-11 containing (and PET positive) lymph nodes, as found in two patients, were also confirmed with the DROP-INβ probe (S/B > 3). The rotational freedom of the DROP-IN design and the ability to manipulate the probe with the prograsp tool allowed the surgeon to perform autonomous beta-tracing.

CONCLUSIONS

This study demonstrates the feasibility of beta-radioguided surgery in a robotic context by means of a DROP-INβ detector. When translated to an in vivo setting in the future, this technique could provide a valuable tool in detecting tumor remnants on the prostate surface and in confirmation of PSMA-PET positive lymph nodes.

The necessity of IIb dissection in T1-T2N0M0 oral squamous cell carcinoma: protocol for a randomized controlled trial

Background

There is a growing debate on the relationship between health-related quality of life (HRQoL) and patient survival which has been going on for the last few decades. The greatest wish of clinicians is to extend the latter while improving the former. Following neck dissection of early-stage oral carcinoma, “shoulder syndrome” appears due to traction of the accessory nerve during removal of level IIb, which greatly affects patient quality of life. Since occult metastasis in level IIb of early-stage oral carcinoma is extremely low, some surgeons suggest that level IIb can be exempt from dissection to improve the HRQoL. However, other surgeons take the opposite view, and thus there is no consensus on the necessity of IIb dissection in T1–2N0M0 oral squamous cell carcinoma (OSCC).

Methods

We designed a parallel-group, randomized, non-inferiority trial that is supported by Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai, China. We will enroll 522 patients with early oral carcinoma who match the inclusion criteria, and compare differences in 3-year overall survival, progression–free survival (PFS) and HRQoL under different interventions (retention or dissection of level IIb). The primary endpoints will be tested by means of two-sided log-rank tests. Analysis of overall and progression-free survival will be performed in subgroups that were defined according to stratification factors with the use of univariate Cox analysis. In addition, we will use post-hoc subgroup analyses on the basis of histological factors that were known to have effects on survival, such as death of invasion of the primary tumor. To evaluate HRQoL, we will choose the Constant–Murley scale to measure shoulder function.

Discussion

Currently, there are no randomized controlled trials with large sample sizes on the necessity of IIB dissection in T1–T2N0M0 OSCC. We designed this noninferiority RCT that combines survival rate and HRQoL to assess the feasibility of IIb neck dissection. The result of this trial may guide clinical practice and change the criteria of how early-stage oral cancer is managed. The balance between survival and HRQoL in this trial is based on early-stage breast cancer treatment and may provide new ideas for other malignancies.

Trial registration

Chinese Clinical Trial Registry, ChiCTR1800019128. Registered on 26 October 2018.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3683-y) contains supplementary material, which is available to authorized users.

Topographical distribution of sentinel nodes and metastases from T1-T2 oral squamous cell carcinomas

OBJECTIVE

The objective is to investigate the topographical distribution of sentinel nodes (SNs) and lymph node metastases in T1-2cN0 oral squamous cell carcinomas (OSCCs).

METHODS

The study entailed a prospective enrolment of 220 patients with clinical T1-2N0 OSCCs who underwent preoperative lymphoscintigraphy (LSG) followed by gamma probe-guided sentinel lymph node biopsy (SLNB). Patients with positive SNs were treated with completion neck dissection. Excised lymph nodes were grouped into the neck level according to the international guidelines.

RESULTS

The SN detection rate by LSG was 99.1%. Patients with midline tumours had bilateral lymphatic drainage on LSG in 15/21 (71.5%). There were 45/199 (22.6%) patients with lateralised tumours that had unexpected bilateral or contralateral drainage patterns on LSG. Fifty-five patients (25.0%) were SLNB positive, and metastases were found in 72/781 (9.2%) of the excised SNs. Metastatic involvement of neck level IV was rare and only observed in patients with anterior tongue cancer. No patients had level V involvement. Eleven patients developed isolated cervical recurrences, with no new primary tumour as origin. The SLNB procedure ensured an overall sensitivity of 83.3% and a negative predictive value of 93.3%.

CONCLUSION

Completion neck dissection of level I-III in SLNB-positive patients might be sufficient in most patients with OSCC except patients with anterior tongue cancer, but further studies are needed to support this potential therapeutic algorithm. Our study showed that SLNB was helpful in clarifying unexpected bilateral or contralateral metastatic drainage patterns. In our cohort, 8/55 patients with occult metastasis would have been missed by elective neck dissection of the ipsilateral neck.

AHNS Series: Do you know your guidelines? Evidence-based management of oral cavity cancers

Oral cavity squamous cell carcinoma (OCSCC) is the most common nonmelanoma head and neck cancer in the world, with an estimated 405 000 new cases expected each year. Subsites of the oral cavity include the alveolar ridge, buccal mucosa, anterior tongue, tonsillar pillar, retromolar trigone, hard palate, gingiva, and floor of the mouth. In this issue of the AHNS "Do you know your guidelines?" series, we review the evidence-based approach to the management of oral cavity carcinomas based on the framework provided by the National Comprehensive Cancer Network (NCCN) Clinical Practice Guidelines in Oncology.