The problem is that currently the mutational status is frequently made on the tissue resulting from the initial tumor biopsy, and as it is not excluded that the evolution of the biology of the metastasis reports a different genomic status, the only theoretical solution is then to make biopsy systematically on metastasis, what is not always technically possible. The problem still complicates when the investigators know that the biology of the tumor may evolve in time, particularly under treatment, with appearance of chemotherapy resistant clones. The monitoring of the genomic status of the tumor thus appears to be a crucial stake in the next years in cancer research as far as the efficiency of numerous therapeutic targeted put at the disposal of the clinician, depends on it largely. The repeated access to tumor tissue, during the follow-up of the patient in treatment, seems from then on indispensable to guide prematurely the therapeutics, in particular by stopping a targeted therapeutics which the investigators know that it is not any more going to be effective, and so avoiding exposing the patient to useless toxicity of a treatment often extremely expensive, and of which usage should have to be reserved to patient who could respond to it.