The access to the circulating tumor cells in the blood of patients is a repeatable, not invasive technique (blood test) and henceforth accessible thanks to a technique using a magnetic sorting of the tumor cells selected by an antibody directed against the tumor antigen EpCAM. This new technology (CellSearch, Veridex system) totally standardized and automated, allows from a total sample of blood of the patient, to determine the quantity of circulating tumor cells (CTC).The number of CTC seems to constitute in recent studies, a powerful prognosis tool at the moment diagnosis, but also during treatment, according to its decrease or not under chemotherapy. In United States, the Food and Drug Administration (FDA) recently approved the use of this system for the quantification of the CTCs in the care of the patients affected by breast, colon, and prostate cancer. The CellSearch system will probably become in the future years an indispensable tool to help the clinicians to encircle better the prognosis of their patient. This technology already allows to realize besides a quantification, the isolation of viable CTCs, from which the genetic material can be extracted, amplified thus potentially analyzed. The investigators thus see all the interest which such a device can represent in the non invasive monitoring of the patients under treatment targeting molecular abnormality susceptible to evolve in time. The investigators thus propose to study thanks to the system CellSearch the feasibility of the research for the mutation of K-Ras and EGFR in the CTC of patients carriers of a metastatic non small cells bronchial carcinoma.