Pilot study on the validation of fluorescence imaging of lymph nodes during colorectal lymphadenectomy, using indocyanine green.

Adjuvant systemic chemotherapy is indicated in colorectal carcinoma (CRC)
patients with metastatic lymph nodes (LN's), resulting in a 30% relative
increase in survival.
To assess the actual LN status optimal examination by means of adequate LN
dissection is mandatory. The Dutch CRC treatment guidelines require a minimum
of 10 LN*s to be examined for adequate staging. However, it has recently been
demonstrated that often a median number of 6 LN*s are examined among CRC
patients in the Netherlands. This may be due to the difficulty of
intraoperative detection of these LN*s, demanding a technique that enables the
surgeon for more accurate identification of LN*s during the surgical procedure.
In addition, the intraoperative detection of the sentinel lymph node will allow
the pathologist to examine in more detail the possibility of metastasis.
Where other carcinomas such as breast cancer, have well established techniques
to guide SLN surgery, no such technique is yet available for CRC.
Recent studies suggest that a new procedure, using an FDA approved, fluorescent
(indocynanine green; ICG), could allow for highly sensitive detection of the
lymphatic outflow track and draining LN*s. Therefore, ICG is expected to
improve lymphatic mapping, SLN detection and subsequent lymphadenectomy.
Consequently, staging of CRC and postoperative outcome will improve.

Feasibility study: The potential use of intraoperative, ICG based, fluorescence
imaging of LN*s during CRC lymphadenectomy.

No special patient preparation is required. During surgery 4 ml of ICG solution
(25 mg) will be injected in/around the tumor (similar to standard patent blue
procedure in breast cancer). Dynamic imaging by a dedicated camera during 15
min post injection will help detect the lymphatic outflow track with
visualization of the majority of draining lymph nodes, including the first
draining lymph node (sentinel node). Subsequently, all the fluorescent LN*s
will be resected and marked for PA.

Other than intraoperative injection and tracking of ICG, this study will not be
any different of standard procedures. During the ICG-injection the patient will
be anesthetised and therefore experience no extra burden. Operating time may,
however, be prolonged by 15 min. due to the imaging procedure. Conversely, the
value of an improved and more adequate lymphadenectomy could have a major
impact in the improvement of staging and postoperative outcome in CRC patients.
In rare cases (< 1/10.000) nausea, urticaria and anaphylactic reactions have
been reported. Because of the proposed exclusion criteria, these numbers will
in fact be lower within this study.