Joint symposium 2009 on carbon ion radiotherapy.

The clinical results of carbon ion therapy pioneered in Japan remain promising, especially in a wide range of cancers that are difficult to treat using X-rays. As well as producing impressive tumour control rates, there appears to be a marked reduction in radiation-related toxicity, as would be expected from the advantageous dose distributions. There remain some controversial research-related issues, such as the radiobiological conversion methods, dose fractionation, and which form of accelerator systems and treatment delivery systems should be used. Cost is a major issue, which is being addressed by the use of far fewer treatments than with X-ray therapy. The expansion of this form of treatment in Japan and mainland Europe will provide opportunities for a large research portfolio, which is necessary to optimise this kinder form of radiotherapy.