Sentinel Lymph Node Identification in Colon Cancer with Robotic Near Infrared Fluorescent Imaging System

Giuseppe Spinoglio, MD¹, Alessandra Marano, MD¹, Fabio Priora, MD², Luca M Lenti, PhD², Ferruccio Ravazzoni, PhD², Giampaolo Formisano, MD³. ¹Humanitas Clinical and Research Center, Rozzano, Italy, ²SS Antonio and Biagio Hospital, Alessandria, Italy, ³Misericordia Hospital, Grosseto, Italy

Objective

Patients affected by stages I and II colon cancer may experience locoregional recurrence or distant metastases up to 30% maybe due to missed nodal metastases at standard histological examination (single-section hematoxylin and eosin- H&E-staining). The sentinel lymph node (SLN) concept could offer a solution since its primary purpose is to upstage tumors whose metastases would remain undetected by conventional pathological examination and to identify aberrant lymphatic drainage, thus improving cancer staging. However, there is currently a paucity of evidence to support such tailored treatment. The objectives of the study are to identify in “real time” SLN in 40 patients affected by colon cancer with robotic Indocyanine green (ICG) fluorescence imaging system and to histologically evaluate the SLN harvested.

Description

Under Ethical Committe approval for Study Protocols, from July 2014 to December 2014, we performed at SS.Antonio and Biagio Hospital, Alessandria, Italy a total of 22 robotic colon procedures (14 right colectomies, 8 left colectomies) for preoperative stage I and II cancer with SLN biopsy with near-infrared (NIR) ICG fluorescence imaging system. After robotic docking, a subserosal peritumoral injection of ICG (mean dose 1 mg) was implemented. Within 20 minutes, the first one to three LN, accumulating ICG and so appearing in “real time” as shining fluorescent spot was defined as SLN(s), classified, removed, sent to the pathology and evaluated with H&E staining. If SLNs evaluation was negative, a multi-sectioning and additional immunohistochemistry was performed to detect any IHC or micrometastasis. At the end of the SLN biopsy, standard surgery with regional LN dissection was carried out as usual.

Preliminary results

To date, 22 out of 40 scheduled patients have been enrolled. No adverse reaction occurred and the procedure took an extra-time of 22.6 minutes. SLNs were identified in 16 out of 22 patients (detection rate 72.3%) and the mean number of harvested SLNs was 2. Among SLNs, only one confirmed to be metastatic at the immunohistochemistry (6%). Sensitivity was 47% and no aberrant lymphatic drainage was detected.

Conclusions

The application of fluorescence in robotic surgery for SLN biopsy may potentially improve staging in patients affected by N0 colon cancer. It’s a simple, safe and fast method. Detection rate is acceptable but sensitivity is still very low. Further investigations are needed to address its shortcomings and pitfalls.