Detection of the ‘systemic sentinel lymph node’ in colorectal cancer using fluorescence imaging after indocyanine green intravenous injection: A feasibility study (Preprint)

BACKGROUND Nodal staging is a major concern in colorectal cancer (CRC) as it is an important prognostic factor. Several techniques have been developed to increase the accuracy of nodal staging that could potentially improve patient treatment and prognosis. Sentinel lymph node (SLN) detection has been shown to accurately reflect nodal status in various tumors and has become the standard procedure in nodal staging of breast cancer and melanoma. However, in CRC, SLN detection techniques are still controversial as the sensitivity reported in the literature varies from one study to another. Recently, indocyanine green (ICG) fluorescence-guided surgery has been reported to be a useful technique for detection of macroscopic and microscopic metastatic deposits in lymph nodes (LN) after intravenous administration (IV) of ICG. However, no studies have focused on the potential role of SLN detection after systemic ICG administration, so-called 'systemic' SLNs (sSLNs), and on the correspondence between the identification of the sentinel LN by standard local injection techniques and the detection of fluorescent LNs with this new approach. OBJECTIVE The aim of this protocol is to validate the concept of 'SLNs' identified by fluorescence imaging (FI) after IV injection of ICG and to compare them with SLNs detected by the standard blue dye technique. METHODS The SeLyNoFI study is a diagnostic, single-arm, open-label feasibility study, including patients with colorectal adenocarcinoma with or without metastatic disease admitted for elective colorectal resection of the primary tumor. This study evaluates the feasibility of a new approach for improving the accuracy of nodal staging using FI after IV ICG administration. Sensitivity, positive predictive value, and accuracy of the classical blue dye technique and of the investigatory FI technique will be calculated. Translational research will be proposed, if applicable. RESULTS The potential correlation between two different approaches to detect SLNs offers new strategies for improving the accuracy of nodal staging in colorectal cancer. This new concept of the 'systemic' SLN and a greater understanding of the interactions between sSLNs and 'standard' SLNs may provide important information regarding the underlying mechanism of primary tumor lymphatic drainage. The EPR effect can also play a role in the fluorescence of sSLNs, especially if these lymph nodes are inflammatory. In this case, we can even imagine that this new technique will highlight more positive lymph nodes. CONCLUSIONS The results of this clinical study evaluating a new intraoperative procedure could help to improve nodal staging in patients with colorectal cancer. CLINICALTRIAL 2020-002521-29.