Carbon Ions radiotherapy, also called Heavy Ions Particle Therapy or Hadron Therapy, has proven very good in radioresistant and hypoxic tumors. The heavier particles in the carbon ion beam scatters less in healthy tissue on its way to the Bragg Peak and delivers a more conformal dose to the tumor than any other currently used form of radiation therapy. It also inflicts more permanent damage to the tumor cells compared to other radiotherapy, often including double-strand DNA breaks which are more difficult for the tumor cells to repair than single strand DNA breaks.
There are only a few light ion (carbon ion) facilities in the world, the most prominent being NIRS (National Institute of Radiological Sciences) in Chiba, near Tokyo, Japan. Dr. Hirohiko Tsujii and his team at NIRS have treated over 11 000 patients since 1994 under more than 50 clinical research protocols with extensive follow-up and excellent results.
Other Light Ions Particle Therapy facilities providing carbon ion therapy include HIT at DKFZ in Heidelberg, Hyogo University in Japan, Gunma University in Japan and soon also CNAO in Pavia near Milan, Italy.
Links to several different proton and ion therapy facilities can be found here