This study is a clinical feasibility trial that will contribute to the clarification of whether sentinel node mapping with indocyanine green (ICG) provides a better basis for staging of colorectal cancer.

The patients assigned for colon cancer will be operated as planned using laparoscopic techniques and the operation follows the normal procedure, in addition a sentinel node mapping is performed.

Indocyanine green is injected around the tumor by laparoscopic technique, the fluorescence is controlled and after 20 minutes the surgeon looks for sentinel nodes in a standardized manner. In the meantime, the surgeon proceeds with the operation as usual, except that the mesocolon can be resected only after sentinel node mapping has been performed.

After surgery the surgeon and the pathologist inspect the resected colon together and agree on D1, D2 and D3 margins. Any marked sentinel node(s) is verified and the location is checked on the colon diagram on the case report form. In addition, an ex vivo sentinel node mapping will be performed by the pathologist right after the surgery has ended. This is done to investigate if it is the same lymph nodes there will be identified by ex vivo as by intraoperative (in vivo) sentinel node mapping.

The lymph nodes in the resected colon and mesocolon are all analysed. Sentinel nodes and an equal number of randomly chosen non-sentinel nodes will be analysed further with additional sections and immune histochemistry.

Inclusion Criteria:

• Male and female patients above 18 years of age scheduled for laparoscopic colon cancer surgery in the department of Surgery, Herlev Hospital or Roskilde Hospital.

Exclusion Criteria:

• iodine allergy
• Poor kidney function (as it imply an increased risk of allergic reaction), estimated glomerular filtration rate should be above 40 ml/min.
• Liver cirrhosis, Child-Pugh-score B and C [14]
• Pregnancy and lactation
• Previous anaphylactic reaction to a dye injection
• Previous abdominal surgery