IMPORTANCE: Indocyanine green (ICG) fluorescence-guided sentinel lymph node (SLN) biopsy has been developed as a new technique for breast cancer with no use of radioisotope (RI). However, ICG method alone is not suitable for SLN biopsy in patients with oral cancer because of poor transcutaneous identification of fluorescence signal through platysma and sternoclidomastoid muscle.
OBJECTIVE: To assess the utility of a novel SLN biopsy technique using a combined method of preoperative CT lymphography followed by the intraoperative ICG fluorescence method for early tongue cancer patients.
DESIGN, SETTING, AND PARTICIPANTS: Prospective study was performed for eighteen patients (8 males and 10 females) with previously untreated cN0 early tongue cancer (squamous cell carcinoma) including 7 of T1N0 and 11 of T2N0 patients (7th edition of the AJCC / UICC TNM classification).
INTERVENTIONS: As a preoperative SLN mapping, CT lymphography was performed at the day before SLN biopsy on patients who were attached a lattice marker to the neck skin. SLN was determined as the firstly enhanced lymph node following peri-tumoral injection of iopamidol and its location was estimated in relation to the lattice marker. For SLN biopsy, minimum skin incision was made according to the pre-determined location of SLNs. ICG solution was injected into the peritumoral region and SLNs were excised under the ICG fluorescence guidance.
MAIN OUTCOMES AND MEASURES: Success rate of preoperative SLN mapping by CT lymphography and the number of SLN successfully identified by intraoperative ICG fluorescence method were evaluated. Following the removal of SLNs, metastasis to SLNs was examined by the intraoperative frozen section.
RESULTS: Among 18 patients, SLNs could be mapped by preoperative CT lymphography in 16 patients (88.9%). At least one SLN was successfully identified in all these 16 patients with intraoperative ICG fluorescence method, resulting in the success rate of 88.9% to excise the SLNs by this combination method. Among 16 patients who were excised their SLNs, metastases to SLNs were found in 5 patients (31.3%): 2 patients of T1N0 and 3 of late T2N0.
CONCLUSIONS AND RELEVANCE: The novel SLN biopsy technique, preoperative CT lymphography mapping combined with the intraoperative ICG fluorescence method, achieved a high success rate to identify the SLN in cN0 tongue cancer patients. Preoperative CT lymphography mapping and intraoperative ICG fluorescence-guided SLN biopsy is simple, cost-effective, and useful combination method for SLN biopsy in early stage tongue cancer without using RI.