Natural history of tumors is a poorly studied subject, the clinical evidence of some tumors aggressiveness as opposed to some other's indolent behavior has never been formally assessed in daily practice or in clinical studies and remains largely unpredictable. The patient's populations are in fact a mix between different tumoral phenotypes that while carrying the same apparent disease evolve with different outcomes.~We hypothesize that,in a population of patients with advanced colorectal cancer for which no known effective therapy is available, measuring the spontaneous evolution of tumoral metabolic progression index by serial FGD PET-CT and Diffusion MRI can show that tumor growth rate is related to the patient's outcome, and that serial FDG PET-CT and Diffusion MRI are able to measure it.~If the hypothesis is verified, this finding could:~Allow to define therapeutic strategies according to the tumoral metabolic progression index.~Limit the need for randomization in the early drug development phases as each patient could be considered as his own control.~To stratify patients according to their baseline metabolic growth rate in randomized controlled trials with overall survival as an endpoint.
The purpose of this study is to assess whether in a population of patients with advanced colorectal cancer for which no known effective therapy is available, measuring the spontaneous evolution of tumoral metabolic progression index by serial FGD PET-CT and Diffusion MRI can show that tumor growth rate is related to the patient's outcome, and that serial FDG PET-CT and Diffusion MRI are able to measure it.