Disclosed is a system including (1) an injection device including injectable magnetizable nanoparticles and a component for injecting the same, and (2) a unit for applying a constraint physically and/or mechanically to a tumor associated to an neoangiogenic network where, after having been injected, the particles are retained. Also disclosed is a method for treating tumors, especially tumors associated with a neoangiogenic network, including the steps of: injecting a composition including magnetizable nanoparticles optionally performing imaging using an imaging device to detect a concentration of nanoparticles retained in the neoangiogenic network and applying a contact-free constraint onto a tumor in vivo, by a gradient of magnetic field and the application being directed to the tumor region.
