The study is designed to elucidate whether carbon black suspension endoscopic tattoo enhances visibility of lymph nodes or tumor tissue on dissection of colonic surgical specimen, thereby making improvement in staging defined as better pTNM stage via better visualisation of carbon marked metastatic or sentinel lymph nodes or marked primary tumor or adjacent tissues.

Other objectives are:

• to assess intraoperative visibility of carbon black tattoo in the tumor region and surrounding tissues
• to assess microscopic distribution of carbon ink in the layers of the colonic wall and adjacent tissues
• to assess complications related to carbon black tattoo procedure like microscopic fibrosis, micro- or macroscopic scarring, inflammatory reactions
• to assess long-term effects of ink injections on control endoscopies at 6 and 12 months
• to assess dissection time in tattooed-non tattooed lymphatic tissues

Inclusion Criteria:

• Male or female aged 18 years or above undergoing colonoscopy for suspected colonic malignancy
• Participant is able to give informed consent for participation in the study
• Patient is presumably selected for surgery within 30 days following tattoo injection

Exclusion Criteria:

• Patients under the age of 18
• Patients unable to give informed consent or ineligible for surgery
• Tumor in the coecum dome or in the rectum (<15 cm)
• Known allergy to suspension ingredients