PD19-04 VALIDATION OF HYBRID ICG-99mTc-NANOCOLLOID FOR SENTINEL NODE BIOPSY IN A LARGE COHORT OF PENILE CANCER PATIENTS

Abstract

INTRODUCTION AND OBJECTIVE: Dynamic sentinel node (SN) biopsy is an invasive lymph node (LN) staging method that is typically performed using 99mTc-nanocolloid combined with blue dye to detect micro-metastatic disease for ≥T1G2 penile cancer (PC) patients with no palpable inguinal LNs (cN0). Recent reports suggested that the hybrid tracer indocyanine green (ICG)-99mTc-nanocolloid may improve intraoperative optical SN identification relative to the blue dye. However, this evidence is supported by small sample size series. The aim of the current study was to confirm these findings relying on the largest single center cohort of PC patients who underwent SN biopsy using ICG-99mTc-nanocolloid and blue dye METHODS: 404 patients with ≥T1G2N0 penile squamous cell carcinoma were scheduled for SN biopsy and treatment of the primary tumour at a single European centre. Of those, 255 received SN biopsy using ICG-99mTc-nanocolloid and blue dye. After peritumoural injection of ICG-99mTc-nanocolloid, SNs were preoperatively identified based on lymphoscintigraphy and SPECT/CT. Shortly before surgery, blue dye was administered in all patients using the same injection sites as the hybrid tracer. Intraoperatively, SNs were pursued via gamma tracing, visual identification (blue dye) and near-infrared fluorescence imaging (ICG). Intraoperative SN identification rates of blue dye and ICG-99mTc-nanocolloid were compared using a two-sample t-test RESULTS: There were no tracer-related adverse events. Lymphoscintigraphy and SPECT/CT visualized at least one SN in all patients. All preoperatively defined SNs were intra-operatively identified using a combination of radio-, fluorescence- and blue dye guidance. A total of 841 SNs were excised (median 3 SNs per patient; range 1-9). Of these, 95% were visible with fluorescence imaging, while only 56% were stained by blue dye (p<0.001). Pathologic analyses of the 841 SNs removed, identified 58 positive nodes in 43 patients. Of those, 100% (n=58) and 69% (n=40) were fluorescent or stained blue, respectively. In 45 patients, blue dye did not identify any LN. Of these patients, 7% had positive nodes. Conversely, fluorescence imaging using the hybrid tracer enabled optical detection of at least one SN in all patients CONCLUSIONS: The use of fluorescence improved the optical detection rate of SNs of 39% relative to blue dye. Its use is safe and can replace blue dye for SN biopsy in patients with PC Source of Funding: None