Role of Indocyanine Green in Mapping Sentinel Cervical Lymph Node Involvement in Patients of Oral Squamous Cell Carcinoma - Preliminary Data from a University Hospital

Abstract

Introduction: Lymph node (LN) positivity is an important determinant in a patient of oral SCC. Sentinel lymph node (SLN) biopsy may aid in minimizing the extent of elective neck dissection (ND). ICG dye facilitates the visualization of lymphatic vessels, sentinel nodes, and provide high penetration during surgery. Methods: It is a prospective observational study in 2021-2022. N = 32 patients of oral SCC were injected with 1mL of ICG submucosally in 4 quadrant fashion (3,6,9 and 12 o’clock). After elevation of platysma flap and posterior retraction of sternocleidomastoid muscle (15 minutes after injecting ICG), fluorescing LNs were detected using NIR (Near Infra-red) fluorescence imaging (STRYKER AIM 1588 camera system) and were sent for frozen section and histopathological examination (HPE). Results: Majority were carcinoma buccal mucosa (53%), followed by tongue (22%) and GB sulcus (12.5%). Most common method of ND was modified radical ND 78%, followed by supraomohyoid 12.5%, extended supraomohyoid 6.25%, radical ND 3.1%. A total of 755 LNs were harvested. 82 lymph nodes were identified as SLN using ICG method. Level Ib was identified as SLN in 26/32 of the cases, followed by level Ia and level IIa (3/32 cases each). 22 out of 82 SLN were positive in frozen section and HPE respectively with a sensitivity of 100%, specificity of 91.8% and NPV (negative predictive value) of 100 %. Routine pathology demonstrated occult metastasis exclusively in SLN in 10 cases (31.25%). Conclusion: NIR using ICG is a feasible and promising method for SLN biopsy in cN0 oral SCC.