Feasibility of lateral sentinel lymph node biopsy in medullary thyroid cancer: A surrogate tool for determining prophylactic lateral neck dissection-A pilot study

A combination of pre- and intraoperative techniques identifies sentinel lymph nodes in dogs with thyroid carcinoma: A pilot study

OBJECTIVE

The aim of this study was to develop and describe pre- and intra-operative sentinel lymph node (SLN) mapping techniques in dogs with thyroid carcinoma.

STUDY DESIGN

A prospective, pilot clinical trial was performed.

ANIMALS

Six client-owned dogs with unilateral thyroid carcinoma and no overtly metastatic locoregional lymph nodes (LNs) were enrolled.

METHODS

All dogs underwent preoperative indirect computed tomography (CT)-lymphography (CTL) with peritumoral iohexol injection and intraoperative SLN mapping with peritumoral injection of a visible dye (methylene blue [MB]) and near-infrared (NIR) fluorescent dye (indocyanine green [ICG]). Subsequent LN extirpation and routine thyroidectomy were performed. All excised tissues were evaluated histologically.

RESULTS

Pre- and intra-operative SLN mapping identified at least one SLN in all dogs. A median of one SLN (range, 1-2) was identified on both CTL and intraoperative SLN mapping. Identified SLNs included medial retropharyngeal, cranial deep cervical, and superficial cervical LNs. Variability between pre- and intra-operative SLN findings occurred in 3/6 dogs. A median of two LNs (range, 1-3) were extirpated for each dog. Metastatic carcinoma was diagnosed in extirpated LNs in 2/6 dogs and 3/12 extirpated LNs.

CONCLUSION

In this pilot study, preoperative CTL and intraoperative MB and ICG/NIR allowed for identification of SLNs in dogs with thyroid carcinoma.

CLINICAL SIGNIFICANCE

Sentinel lymph nodes were identified and extirpated using the described techniques, with nodal metastasis identified in a subset of these dogs due to SLN mapping. Large-scale, powered studies are needed to accurately determine the incidence and prognostic significance of nodal metastasis identified by SLN mapping and extirpation in dogs with thyroid carcinoma.

Medullary Thyroid Cancer: Single Institute Experience Over 3 Decades and Risk Factors for Recurrence

CONTEXT

Medullary thyroid cancer (MTC) has a historic recurrence rate up to 50%, and surgery remains the only cure.

OBJECTIVE

This study aims to assess factors related to recurrence and metastatic spread in MTC.

METHODS

Retrospective chart review was performed from 1990 to 2023 at a single specialized tertiary care referral center. Descriptive analysis and regression models were used for analysis. Sixty-eight patients with MTC, who underwent surgery, were included and the main outcome measure was recurrence.

RESULTS

Mean age at diagnosis was 54.9 years (42.2-64.1), 65% (n = 44) females. Lymph node and distant metastases were found in 24% (n = 16) and 4% (n = 3), respectively. RET mutations were present in 52% (n = 35): MTC risk levels were highest 6%, high 7%, and moderate 39%. Mean tumor size was 1.9 cm (1.2-3.2) and mean preoperative calcitonin was 504.4 pg/mL (133.2-1833.8). Total thyroidectomy (TT) was performed in 10 patients, TT + central neck dissection (CND) in 28, and TT + CND + lateral neck dissection (LND) in 25. On final pathology, 40% had positive central nodes and 25% had positive lateral nodes. Recurrence was 22%, median follow-up 4.7 years (1.2-28.0). Male gender (hazard ratio [HR] 5.81, P = .021), positive lateral neck nodes (HR 8.10, P = .011), and high/highest MTC risk level RET mutations (HR 8.66, P = .004) were significantly associated with recurrence. Preoperative calcitonin >2175 pg/mL was a strong predictor for distant metastasis (area under the curve [AUC] 0.893) and a good predictor for lateral neck disease (AUC 0.706). Extent of surgery was not significantly associated with recurrence (P = .634).

CONCLUSION

One of 4 patients undergoing surgery for MTC will recur. Risk factors associated with recurrence are male gender, lateral lymph node metastasis, and high/highest MTC risk level mutations, but not necessarily surgery type. Preoperative calcitonin >2175 pg/mL is suggestive of advanced disease and should prompt further evaluation.

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).

Sentinel lymph node mapping: current applications and future perspectives in thyroid carcinoma

Sentinel lymph node (SLN) mapping is a standard, minimally-invasive diagnostic method in the surgical treatment of many solid tumors, as for example melanoma and breast cancer, for detecting the presence of regional nodal metastases. A negative SLN accurately indicates the absence of metastases in the other regional lymph nodes (LN), thus avoiding unnecessary lymph nodal dissection. Papillary thyroid carcinoma (PTC) is the most common type of thyroid carcinoma (TC) with cervical LN metastases at diagnosis in 20-90%, and nodal involvement correlates with local persistence/recurrence. The SLN in PTC is an intraoperative method for staging preoperative N0 patients and for detecting metastatic LNs "in and outside" the cervical LN central compartment; it represents an alternative method to prophylactic central neck node dissection. In this review we summarize different methods and results of the use of SLN in TC. The SLN identification techniques currently used include the selective vital-dye (VD) method, 99mTc-nanocolloid planar lymphoscintigraphy with intraoperative use of a hand-held gamma probe (LS), the combination LS + VD, and the combination LS and preoperative SPECT-CT (LS + SPECT/CT). The application of the SLN procedure in TC has been described in many studies, however, the techniques are heterogeneous, and the role of SLN in TC, with indications, results, advantages and limits, is still debated.

Sentinel node mapping in thyroid cancer: an overview

In this paper we describe the current status of sentinel node mapping (SNM) in thyroid tumors and its potential perspectives. SNM in thyroid cancer has been tested since the end of the twentieth century, mainly in papillary thyroid cancer (PTC) and in medullary thyroid cancer (MTC). In PTC, it has been employed to find occult lymph node metastases in the central compartment of the neck as an alternative or indication for prophylactic dissection, by several methods. All of them have proven effective in spotting sentinel nodes, but the results have been somewhat diminished by uncertainty about the clinical significance of occult metastases in differentiated thyroid cancer. SNM in MTC has also been used to find occult lymph node metastases in the lateral compartments of the neck, also with excellent results hindered by a similar doubt about the real clinical significance of MTC micrometastases. Well designed, adequately sized randomized controlled trials are lacking, so SNM in thyroid tumors remains an interesting yet experimental methodology. New technology is emerging that could facilitate such studies, which could add solid information about the clinical significance of occult neck metastases in thyroid 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).