Radioactive nanosized colloids and indocyanine green identify the same sentinel lymph nodes in oral squamous cell carcinoma

First study on the efficiency of 99mTc-rituximab for sentinel lymph node mapping and biopsy in oral squamous cell carcinoma

OBJECTIVE

To explore the clinical efficiency of using the sentinel lymph node (SLN) imaging agent 99mTc-rituximab for lymphoscintigraphy and SLN biopsy (SLNB) in oral squamous cell carcinoma (OSCC) patients.

METHODS

A retrospective study was conducted on 23 patients with OSCC who underwent 99mTc-rituximab lymphoscintigraphy and SLNB. The cohort comprised 16 men (69.6%) and 7 women (30.4%) with a median age of 64.0 years (range: 33-90 years). All patients received a preoperative peritumoral injection of 99mTc-rituximab. The SLN detection rates (SDRs) of SLN imaging and SLNB were analyzed. The localizations of SLNs were counted. Patients were followed up after surgery. Differences were considered significant for a p-value of less than 0.05.

RESULTS

The SDRs of lymphoscintigraphy and SLNB were 91.3% (21/23) and 100.0% (23/23), respectively. The SDRs of lymphoscintigraphy for patients in pathological stages I/II and III/IVa were 100.0% (15/15) and 75.0% (6/8), respectively. Among the 2 patients with negative imaging results, both were stage IVa and both had SLN metastasis. The SLNs were located in levels Ib, IIa, IIb, III, and IV, accounting for 45.0% (18/40), 40.0% (16/40), 10.0% (4/40), 2.5% (1/40), and 2.5% (1/40), respectively. The median follow-up duration was 32.0 months (range: 13.0-68.0 months). During follow-up, none of the 23 patients (100.0%) showed lymph node (LN) metastasis. As a result, the sensitivity, negative predictive value (NPV), and accuracy were all 100.0%.

CONCLUSIONS

The application of 99mTc-rituximab for SLN imaging and SLNB in OSCC patients demonstrated high detection rates and accuracy, holding significant clinical value.

Use of Indocyanine Green Near-Infrared Imaging for Sentinel Lymph Node Biopsy in Early Oral Squamous Cell Carcinoma: A Pilot Study

PURPOSE

The current established technique for sentinel lymph node (SLN) biopsy is preoperative injection of 99mtechnetium-labeled nanosized colloids (99mTc) followed by single photon emission computed tomography and standard computed tomography (SPECT/CT) with subsequent intraoperative gamma probe-guided excision of the SLN. It is however time and resource consuming, causes radiation exposure and morbidity for the patient as the injection is done in the awake patient. Recently near-infrared imaging with indocyanine green (ICG) gained importance in SLN biopsy as a faster and more convenient technique. The objective of our study was to investigate the feasibility of SLN biopsy using ICG-imaging in early oral squamous cell carcinoma (OSCC).

METHODS

Single-centre pilot study of five patients with early-stage OSCC. For all patients, both techniques (99mTc and ICG) were performed. We injected 99mTc preoperatively in the awake patient, followed by SPECT/CT imaging. Intraoperatively ICG was injected around the primary tumor. Then the neck incision was performed according to the SPECT/CT images and SLN were detected by using a gamma probe and near-infrared fluorescence imaging of the ICG-marked lymph nodes intraoperatively. The excised lymph nodes were sent to histopathological examination according to the SLN dissection protocol.

RESULTS

In all five patients sentinel lymph nodes were identified. A total of 7 SLN were identified after injection of 99mTc, imaging with SPECT/CT and intraoperative use of a gamma probe. All these SLN were fluorescent and visible with the ICG technique. In two patients, we could identify additional lymph nodes using the ICG technique. Pathological analysis demonstrated occult metastasis in two of the cases.

CONCLUSIONS

Our study shows that ICG-guided SLN biopsy is a feasible technique, especially in combination with conventional radioisotope method and may help for intraoperative localization of SLN. Validation studies with bigger patient cohorts are needed to prove our results.