Method for treating tumours by capturing copper and/or iron

A method for treating cancer in a patient, the method consisting of steps of:

• (a) in vivo capturing copper and/or iron in the patient by administering an effective amount of a colloidal solution of nanoparticles to said patient by intravenous or intratumoral injection, and
• (b) subjecting the patient to radiotherapy, wherein the nanoparticles act as radiosensitizers,
• wherein the nanoparticles have the following formula:
• [Ch1]n—PS—[Ch2]m, wherein:
• PS is a polysiloxane matrix,
• Ch1 and Ch2 are DOTAGA chelating groups of the following formula (I)
• grafted to the polysiloxane matrix by covalent bonding,
• Ch1 is uncomplexed,
• Ch2 is complexed with a metal cation M2, wherein M2 is the gadolinium cation Gd3+,
• n+m is comprised between 10 and 30, and
• the mean hydrodynamic diameter is comprised between 2 and 8 nm.