Immune Mechanisms After Radiofrequency Ablation of Pulmonary Metastases From Colorectal Cancer Origin

RFA could provide activatory signals and become a source of tumor antigens for the immune system. Generating a massive and transient release of antigens, RFA could boost lymphocyte proliferation and production of inflammatory cytokines in response to tumor extracts. Herein, the investigator aims to demonstrate that RFA can amplify the specific T cell response in metastatic cancer patients. In order to ensure this, he plans to assess and quantify tumor infiltrating lymphocytes through tumoral biopsies. He also plans to measure the CD4, CD8 and NK lymphocytes release, the circulating DNA and tumoral cells release, during RFA of lung metastases. On tumoral biopsies, the expression of PDL-1 ligand will also be evaluated and measured. Participants with bilateral metastases or with 5 or more unilateral metastases will be recruited. The two RFA interventions will be carried out within 4-6 weeks of each other. Blood samples and tumoral biopsies will be performed during each intervention. Biopsies will be performed on a metastasis before the thermal ablation. Blood samples will be performed just before RFA, 30 min after RFA and one day after. Analysis, identification and measure of lymphocytes release will be performed with flow cytometry. All analysis and measurements will be performed in the Bio-Pathology department of Institut Bergonié.