Influence of the Surgical Technique Used for Colectomies on the Concentration of Circulating Tumor DNA and the Presence of Circulating Tumor Cells: Comparison of the "no Touch" Technic With Either First Clamping of the Mesenteric Vessels or First Mobilization of the Tumor Followed by Clamping.

Colectomy is the most commonly used therapeutic approach for the treatment of non-metastatic colorectal cancer. This approach is generally very effective however the rate of recurrence and the appearance of metachronous metastasis remains a major problem in the postoperative period. One of the hypothesis that can explain this tumor progression is the dissemination of tumor cells at the time of tumor mobilization. In this work, we wish to verify this hypothesis by comparing two surgical technics used in our department for left or right colectomies: respectively either first section of the mesenteric vessels followed by the mobilization of the tumor or first mobilization of the tumor followed by the section of the mesenteric vessels. To evaluate the dissemination, we will study two disseminations markers that have shown their prognostic value: i) circulating tumor cells (which represent a direct marker of dissemination) and ii) tumor circulating DNA (which is an indirect marker) but has the advantage of being more representative of all tumor clones and therefore the tumor burden released into the blood at the time of surgery).