Peritoneal carcinomatosis (PC), a tumoral tumor of the peritoneum, is a frequent metastatic localization of colorectal cancer (CRC, 13%). Long regarded as a palliative situation, its management has progressed significantly with a curative treatment based on a complete cytoreduction surgery coupled with intraperitoneal hyperthermic chemotherapy. However current screening tools, tumor markers (ACE, CA19-9, CA125) and abdominopelvic CT scan are insufficient, to diagnose CP early. A non-invasive biomarker, more sensitive and more specific than currently available tumor markers, would be a major advance in oncology. Microparticles (MPs), vesicles from extracellular membrane budding in response to cell activation or apoptosis of different cell types, have been described as implicated in tumor progression, procoagulant activity associated with cancer, and initiation of metastatic niches. A specific microparticulate (microparticulosome) signature has been reported in patients with CRC, particularly in the presence of a thromboembolic event. However, there is currently no data on PMs and their involvement in CP. In addition, CP and surgery coupled with hyperthermic intraperitoneal chemotherapy are major risk factors for thromboembolic complications. The characterization of prothrombotic PMs is therefore essential to predict such event.

The main objective of this project is to characterize the microparticulate signature of CP of colorectal origin and to compare it with that of CP without CP. The secondary objectives are to compare the microparticulate signature obtained on peripheral venous samples and intraoperative tumor samples, evaluate the evolution of the microparticulate signature between the beginning and the end of the intervention, then correlate the peripheral signature to the oncological follow-up of the patients with CP and the occurrence of a thromboembolic event.

Inclusion Criteria:

• patient presenting a peritoneal carcinomatosis from colorectal cancer origin

Exclusion Criteria:

• patient presenting a peritoneal carcinomatosis from other pathologies than colorectal cancer origin