A Multimodal Protocol Combining ^99mTc-Tilmanocept with Indocyanine Green Fluorescence Lympho-Angiography for Sentinel Lymph Node Biopsy in Early-Stage Oral Cancer: A Case Series

Abstract

Sentinel lymph node biopsy (SLNB) is currently considered as a viable alternative to elective neck dissection (END) for the management of cN0 oral cavity squamous cell carcinoma (OCSCC). However, some difficulties were detected in sentinel lymph node (SLN) identification in floor of mouth (FOM) and ventral tongue tumors because of the so-called “shine-through radioactivity” of the injection site, which may mask nodal hotspots in proximity. We assessed the feasibility and the potential strengths of combining 99mTc-Tilmanocept with indocyanine green (ICG) fluorescence lympho-angiography in a dedicated multimodal protocol for SLNB in T1/T2N0 oral cancer to evaluate the synergistic role of each of these two tracers in providing the appropriate sensitivity and ease of learning, even in such a critical anatomical subsite. A detailed, stepwise description of our multimodal protocol is provided, together with the presentation of its application in two cases of early-stage ventral tongue tumors. Radioactive guidance with 99mTc-Tilmanocept was used preoperatively to perform planar lymphoscintigraphy and single-photon emission computed tomography/computed tomography and to define the nodal hotspot(s) and the surgical “roadmap”. In addition, it was used intraoperatively to pinpoint the SLN location within each nodal hotspot with high specificity but limited spatial resolution. Optical guidance with ICG injection at the tumor bed and near-infrared fluorescence imaging was then added, providing intuitive intraoperative guidance within each nodal hotspot with high spatial resolution. Our small experience with this protocol is illustrated and future perspectives are highlighted.

Keywords

• tilmanocept
• indocyanine green
• sentinel lymph node biopsy
• early stage
• oral cancer