*A pilot study to assess the safety and feasibility of fluorescent sentinel lymph node identification in colon carcinoma using Indocyanine green and nanocolloid*

The gold standard for the treatment of colon carcinoma consists of the surgical
en-bloc segmental resection, including the adjacent mesocolon containing the
draining lymph nodes. Analysis of these lymph nodes is important, since lymph
node status is one of the most important factors determining the use of
adjuvant chemotherapy. Although patients with tumour stage I and II do not have
lymph node metastasis, 15-20% develop recurrent disease. Several studies
suggest that ultrastaging techniques such as immunohistochemistry (IHC) or
reverse transcriptase polymerase chain reaction (RT-PCR) using multilevel
slicing result in upstaging of 14-18% of patients, due to newly found (micro)
metastasis. Furthermore, several studies indicate that these micrometastasis
are correlated with a significantly poorer prognosis, subsequently suggesting
that this subgroup of patients might benefit of adjuvant chemotherapy.

However, ultrastaging techniques are labour- and cost intensive, and are
therefore not suitable for analyses of all lymph nodes that have been collected
during segmental colectomy. Sentinel lymph node (SLN) identification in colon
carcinoma might overcome this problem by detecting the draining lymph node of
the tumour, with the highest chance of containing metastatic tumour cells.
Several studies aimed at SLN identification in colon carcinoma have been
published, however, early studies using radio-guided or blue-dye guided SLN
identification, showed relatively high rates of false negatives with consequent
low sensitivity rates. Since mesocolon is rather fatty tissue, visualization of
conventional dyes is difficult. Indocyanine green (ICG), which can be
visualized using near infrared (NIR), has been put forward since I is known to
penetrate relatively deep into living tissue.

Nevertheless, results of SLN identification using ICG remain unsatisfying with
high false negative rates and low sensitivity. Most likely this is due to the
fact that these studies included large tumours, patients with massive lymph
node involvement, which are factors known to interfere with lymph drainage
patterns. Furthermore, subserosal injections were frequently used, while it is
suggested that submucosal injections might result in better sensitivity of the
procedure. And finally, all studies in colon carcinoma use ICG alone, while
ICG-nanocolloid is suggested to improve the visibility of ICG, by increasing
the size of the particle complex. Therefore this prospective study aims to
assess the safety and feasibility of lymph node identification using
ICG-nanocolloid in patients with T1-T2 tumours, without gross lymph node
involvement, using peritumoral submucosal injections.

Primary objective:
The primary aim of this pilot study is to assess safety and feasibility of SLN
identification using submucosal peritumoral ICG-nanocolloid injections.

Secondary objectives:
Secondary objectives are assessing detection rate and sensitivity of SLN
identification, assessing the incidence of micrometastases after ultrastaging
and studying adverse reactions towards ICG-nanocolloid.

In case safety and feasibility are adequate during this pilot study, this might
result in setting up a larger multi-centre prospective cohort aimed at
identifying the effectivity of the SLN identification procedure.

This is a single-centre, open-label, non-randomized cohort safety and
feasibility study.

1. Patients are identified at the outpatient clinic and asked for participation
in the study.
2. Patients will be planned for robot-assisted surgical colectomy according to
standard of care (SOC).
3. Mechanical bowel preparation (MBP) will take place one day prior to surgery
4. During segmental colectomy, a colonoscopy will be performed. Subsequently
the gastroenterologist will inject ICG-nanocolloid peritumoral and submucosal.
5. The NIR system of DaVinci Xi (Firefly) is used to visualize the SLN, which
will be marked using a stitch. If an aberrant lymph node is visualized, this
node will be harvested.
6. Segmental colectomy with procurement of the adhering mesocolon will be
performed according SOC.
7. After extraction of the specimen, ex-vivo examination of the specimen using
the Firefly will be performed.
8. Pathological examination will be done using H&E. All tumour negative lymph
nodes will be examined using serial slicing and subsequent IHC and RT-PCR.
9. Postoperative management will be according SOC.

The potential benefits or harms of the patients are based on the difference in
staging that could potentially be an effect of the ultrastaging techniques. If
macrometastases are detected during ultrastaging techniques, patients will be
given adjuvant chemotherapy, however if micrometastases are detected during
ultrastaging techniques, adjuvant chemotherapy is not given. This is according
to the Dutch guideline for colorectal cancer. A potential benefit of this study
could be that patients receive adjuvant chemotherapy, while this was not seen
with regular staging techniques.

Since patients will receive an additional colonoscopy, preceded by an
additional MBP, patient have an additional risk of complications associated
with MBP and colonoscopy, even though the risk is rather small.