Page 35 - Fluorescence-guided cancer surgery

the detection of perigastric lymph node metastasis. The incidence of skip metastasis among patients with gastric cancer and metastasis is reported to be as high as 11%26. The described technique could assist in identifying these potentially involved extra-perigastric lymph nodes.
One of the limitations of this study is the administration technique, which is performed during surgery in the subserosal layer of the gastric wall. Opening the abdominal cavity, and exposing the a ected part of the stomach could damage lymphatic vessels. This potentially hampers lymphatic ow to SLNs and was overcome as much as possible by avoiding dissections near the primary tumor. Besides, injecting the tracer in the submucosal layer seems more appropriate in case of tumor invasion limited to the mucosa or submucosa. However, it is shown that subserosal injection leads to drainage of the tracer to the same lymph nodes as submucosal injection, because of communication through vertical connections of lymphatic vessels in the gastric wall27. These limitations could be overcome by submucosal endoscopic administration of the lymphatic tracer before surgery. One of the additional advantages of this administration technique is that it allows visual tumor demarcation during surgery through the stomach wall, which assists in intraoperative tumor identi cation, and determination of resection margins. Especially in patients who experience good response on neoadjuvant chemotherapy this could be of added value.
Another limitation of the current feasibility study is that no true SLN procedure was performed, but instead intraoperative detection of SLNs. However, all uorescent hotspots that were detected during surgery were directly marked using sutures. After the surgical procedure, they were mapped from the specimen for pathological assessment. By doing this, the same LNs were analyzed as if they would have been resected directly during surgery, and feasibility of ICG:Nanocoll as lymphatic tracer could still be showed.
Finally, pathological assessment of the LNs consisted of standard-of-care transection and hematoxylin and eosin staining. Multiple transections and additional keratin staining could possibly have resulted in the detection of tumor-tissue in the SLNs of the 2 false-negative patients, and thereby increasing accuracy rate. However, small tumor deposits in the detected SLNs were unlikely to be present as the tumor-positive LNs in the specimen were completely e aced by tumor.
SLN detection in gastric cancer 33