Ceramic microspheres 20-30 μm in diameter containing yttrium (Y) and/or phosphorus (P) are useful for intra-arterial radiotherapy because they are activated to β-emitter with moderate half-life by neutron bombardment. Yttrium oxide (Y_2O_3) microspheres with high chemical durability can be obtained by thermal plasma melting method and the radioactive Y_2O_3 microspheres remarkably suppress growth of VX2 tumor transplanted in rabbit liver. Hollow Y_2O_3 microspheres and yttrium phosphate (YPO_4) microspheres have been also developed for intra-arterial radiotherapy. Magnetic microspheres are believed to be useful for intra-arterial hyperthermia of cancer because they generate heat under alternating magnetic field. Silica (SiO_2) microspheres containing magnetite (Fe_3O_4) and maghemite (γ-Fe_2O_3) nanoparticles can be synthesized by sol-gel reaction in water-in-oil (W/O) emulsion and they can generate heat under alternating magnetic field of 100 kHz, 300 Oe. Also, Fe_3O_4 microspheres prepared by aggregation of the iron oxide colloid in W/O emulsion can gradually release alendronate, a typical bisphosphonate. Development of biomedical materials for treatment of cancer is strongly desired to contribute to better health and welfare of patients with cancer diseases.