EAES (European Association for Endoscopic Surgery) Travel Grant

Background: The sentinel lymph node (SLN) mapping is widely used, during oncological surgery, for several type of tumors (Head and Neck, Breast and Melanoma). This procedure can be performed by using both blue dyes and gamma ray-emitting radiotracers. However, both have disadvantages like the involvement of a nuclear medicine physician, or difficulty to identify nodes through fatty tissue. The SLN procedure has been proposed to improve nodal staging even in colorectal cancer patients. Occult tumor cells and micrometastases are easily missed by conventional histopathologic examination. Various retrospective studies have shown poor prognosis for patients with micrometastases compared with patients without metastases. Aim: The aim of this ongoing prospective study was to assess the value of near-infrared (NIR) fluorescence imaging for ex vivo SLN mapping in conventional surgical resection for colorectal tumors and the detection of micrometastases. Materials and Methods: We enrolled 5 consecutive patients undergoing surgery with curative intent for colorectal cancer. All patients underwent a standard oncological laparoscopic resection. After specimen extraction, we submucosally injected a premixed cocktail of the near-infrared lymphatic tracer around the tumor for detection of SLN. Each SLN was investigated with ultrastaging techniques for the detection of micrometastases using serial sectioning and additional immunohistochemistry or reverse transcriptasepolymerase chain reaction. We used the Quest Spectrum™ Platform imaging system for fluorescence imaging. Results: In 100% of patients, we identified at least one sentinel lymph node. Overall, from the specimens were found 64 lymph nodes. A total of 13 SLN were identified. Alfter ultrastaging anatomopathological investigations, no tumor cells nor micrometastases were present in SLN, nor in the remaining nodes. SLN located deeper in the mesenteric fat could easily be identified by NIR fluorescence. Conclusions: We reported our preliminary data of this ongoing prospective study about the use and value of the NIR fluorescence guided surgery to identify the ex vivo SLN in colorectal cancer and micrometastases research. In our series, the histological sentinel lymph nodes’ asset rightly predicts the status of loco-regional nodes.