The invention relates to a stable water-in-oil emulsion composition, comprising: - 20 to 40% (v/v) aqueous phase, in the form of droplets, comprising an anti-cancer agent and a bulking agent selected from the non-ionic macrocyclic chelate complexes with a paramagnetic metal, - 60 to 80% (v/v) lipid phase comprising an iodised oil and at least one surfactant of formula (I) in a proportion, by mass of surfactant with respect to the total volume of the composition, of 0.3 to 5%, the formula (I) of said surfactant being the following: (I) in which: - s is 0 or 1, - m represents an integer from 2 to 30, - R1 represents a group of formula (II), (II) in which n represents an integer from 4 to 10, o represents an integer from 1 to 4, p represents an integer from 3 to 7, q represents an integer from 2 to 10 and r is 0 or 1, - R2 represents a hydrogen atom or is identical to R1, - each R3 independently represents a hydrogen atom or is identical to R1. The invention also relates to the method for preparation of same and use of same in the treatment of cancer and the metastases thereof.
