Page 34 - Fluorescence-guided cancer surgery

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Chapter 2
larger molecules with a hydrodynamic diameter of <100 nm (ICG:Nanocoll) are retained in the SLN23. In the current study, a mean number of 3.1 SLN per patient was found. This lower number of detected SLNs is in accordance with our hypothesis that better retention in SLNs is obtained when a lymphatic tracer with a higher hydrodynamic diameter is used. This highly improves the clinical applicability of SLN detection using NIR uorescence imaging in gastric cancer.
Although the number of patients was limited in the current study, an excellent accuracy rate was obtained in lower pT stages, in which the clinical value of a SLN procedure is becoming more and more accepted. These data are consistent with previous studies where the SLN procedure was performed for T1 and T2 tumors. However, even for advanced gastric cancer, identifying the rst draining lymph nodes can be of added value. In the current study, LNs from 8 patients were identi ed outside the standard resection margin using NIR uorescence imaging; they would otherwise not have been resected. In 2 patients, the extra-detected LNs outside the standard plane of resection contained tumor cells. These LNs were only resected because NIR uorescence imaging identi ed them. Larger studies are needed to determine the additional value of the described technique in advanced gastric cancer.
In 2 patients, tumor-positive LNs were not identi ed using NIR uorescence imaging. One explanation for the false positivity of these LNs might be the fact that these tumors were relatively large, respectively 60 and 45mm diameter, and consequently, adequate injection of the tracer in four quadrants around the tumor might be hampered. However, other uorescent LNs that that did contain tumor cells, were found in tumors with a median size of 52mm (range 27 – 90). Moreover, all 7 of these LNs were completely e aced by tumor tissue. Such LNs lose function, lymph doesn’t ow in or out, and no lymphatic tissue is present to trap the uorescent tracer. Subsequently, these tumor-positive LNs can’t be identi ed, a principle that counts for the SLN procedure in all solid cancers. In one of these patients however, the identi ed SLN was found in the same LN basin as one of the tumor-involved LNs. This underlines the theory that whenever SLNs are visualized, the entire lymph node basin should be resected instead of only the SLN by lymph node picking, because it is shown that most of the metastatic non-SLNs are positioned in the same basin as the detected SLNs24;25.
A well-known di culty in SLN mapping in gastric cancer is the presence of skip metastasis: involvement of extra-perigastric lymph nodes without