Aim of the project is to surveil results after extended lymphadenectomy for right sided colon resection for cancer with different operative techniques. Patients operated for right sided colon cancer will be involved. There are different operative methods used in terms of extend of lymphadenectomy and access (open, laparoscopic and robotic assisted) that are already implemented. The Norwegian standard operation contains less extended lymph node dissection. Patients operated by the standard method will serve as control group. Choice of access and extend of lymph node dissection in Norway is dependant on the surgeon and hospital. At Haukeland University Hospital extend and access of surgery are determined by a multidisciplinary team meeting. More radical surgery might result in more complications and the benefit for the patients in terms of oncological result and survival is uncertain. At Haukeland University Hospital, extended lymphadenectomy has been mostly performed by open surgery. During the study phase we will introduce extended lymphadenectomy by laparoscopy and robotassisted surgery. Hypothesis is that more radical surgery performed by minimal invasive surgery will result in equal or better oncological results, and less complications, shorter hospital stay and better quality of life. As method we choose a prospective observational study. All eligible patients with adenocarcinoma of the right colon without another ongoing oncological treatment for other cancers will be included. Patientdata will be prospectively registered in a web-based database. Aim of the study will be to define the optimal extend of lymphadenectomy to achieve the best oncological result. In addition, we will analyse the results dependent on the surgical access (open, laparoscopic or robotic). The assumed difference between the operative methods is small. Therefore, the study is designed and approved as a multicenter registration in order to achieve the necessary statistical power.