Combining Indocyanine Green and Tc99-nanocolloid does not increase the detection rate of sentinel lymph nodes in early stage cervical cancer compared to Indocyanine Green alone

Abstract

Objective: To investigate whether combining two independent tracers increases the SLN-detection rate in cervical cancer.

Methods: Consecutive women with early stage cervical cancer planned for a robotic radical hysterectomy or a robotic radical trachelectomy with sentinel lymph node (SLN) detection were included. After cervical injections of Indocyanine green (ICG) and Tc⁹⁹-nanocolloid (Tc⁹⁹), near-infrared fluorescence imaging and a gamma probe were used to identify SLNs in the upper and lower paracervical pathways (UPP/LPP). A strict surgical algorithm was adhered to and the SLNs were defined as SLN-ICG, SLN-ICG+Tc⁹⁹ or SLN-Tc⁹⁹. In FIGO-stage ≥IA2 cancers a full pelvic lymph node dissection (PLND) was performed after detection of SLNs. The primary endpoint was the SLN detection rate per tracer and combination of tracers. Secondary endpoints were sensitivity and mapping rates of the SLN algorithm per tracer and combination of tracers.

Results: In the sixty-five analyzed women, the bilateral mapping rate was 98.5% for ICG and 60% for Tc⁹⁹ (p < 0.01). Combining the tracers did not increase the bilateral detection rate. In three women (5%) Tc⁹⁹ identified ICG-negative non-metastatic SLNs without impact on the bilateral detection rate. Eight women (12%) had lymph node metastases (LNMs), all had at least one metastatic SLN. Seven (35%) of the 20 metastatic SLNs were detected by ICG only and 12 (60%) were ICG and Tc⁹⁹ positive.

Conclusion: SLN detection rate was significantly higher using ICG compared with Tc⁹⁹. ICG identified all patients with LNMs. Combining ICG and Tc⁹⁹ did not improve the bilateral detection rate of SLNs.

Trial registration: ClinicalTrials.gov NCT02690259.

Keywords: Cervical cancer; Indocyanine green; Radiotracer; Sentinel lymph node biopsy.