Upstaging nodal status in colorectal cancer using ex vivo fluorescence sentinel lymph node mapping: preliminary results

Abstract

Background

Sentinel lymph node (SLN) mapping using near-infrared fluorescence (NIRF) imaging is a recent technique to improve nodal staging in several tumors. The presence of colorectal cancer (CRC) micro-metastases has recently been defined as N1 disease and no longer as N1mi, determining the need for adjuvant chemotherapy. In CRC, the reported rate of SLN micro-metastases detected by ultrastaging techniques is as high as 30%. The aim of this prospective study is to report the preliminary results of the sensitivity analysis of NIRF imaging for ex vivo SLN mapping and the research of micro-metastases in CRC, in patients with node-negative disease (NND).

Material and methods

On the specimen of 22 CRC patients, 1 mL of ICG (5 mg/mL) was injected submucosally around the tumor to identify SLNs. NND SLNs were further investigated with ultrastaging techniques.

Results

Three-hundred and sixty-three lymph nodes were retrieved (59 SLNs; mean per case: 2.7). The detection, sensitivity and false-negative rate were 100%, 100% and 0% respectively. Ultrastaging investigations showed no micro-metastases in the NND SLNs.

Conclusions

The ex vivo SLN fluorescence-based detection in CRC was confirmed to be easy to perform and reliable. In this preliminary results report of an ongoing study, the SLN assay was congruent with the nodal status, as confirmed by histological investigations.

Keywords:

• Near-infrared fluorescence imaging
• fluorescence-guided surgery
• sentinel lymph node mapping
• colorectal cancer
• ultrastaging

Declaration of interest

Andrea Picchetto_, Lee L. Swanstrom, Fabio Massimo Magliocca_, Annamaria Pronio_, Eleonore Choppin, Stefania La Rocca, and Giancarlo D’Ambrosio have no conflicts of interest or financial ties to disclose. Michele Diana is the recipient of a grant from the French Foundation ARC.