Proton Therapy Congress 2016

Carbon-ion radiotherapy facilities using next generation technologies

Dr Tadashi Kamada – National Institute of Radiological Sciences, Chiba, Japan

My talk today is about carbon-ion therapy. Unfortunately there is no carbon facility in the UK but in Japan there are fifteen particle facilities now in Japan and five of them are using carbon-ion, a bit heavier than proton beam. Carbon has very promising characteristics like a much sharper dose distribution when compared to the protons and much stronger biological effects when compared to the proton or x-ray. It is very attractive but it costs US$150 million in Japan, it is almost double of the proton beam so it’s very difficult to install the facility anywhere in the world now. It has very good characteristics, I mentioned two: biology and physical dose distribution is much better so it can reduce the overall treatment time. For example, prostate cancer usually uses 40 fractions over eight weeks for the patient treatment but with carbon beam we could reduce the overall treatment time to twelve fractions over three weeks. That is quite short so we could treat almost three times more patients with one facility.  It is quite effective for the running of the facility, it is quite advantageous when compared to the proton beam so I think my talk today is about such effectiveness. Even with the huge costs there is still some praise for the carbon beam. In addition to this very short overall treatment time the carbon can cure very radio-resistant tumours like huge size sarcomas. It is very difficult to treat with the conventional radiotherapy or even with the proton beam and sometimes the sarcoma cannot be operated on. In such cases there is no treatment at all, unfortunately at this moment but with carbon it can cure such a very, very poor miserable disease and many young patients are suffering from such advanced sarcomas. But carbon could be a last resort for such patients. This is my talk today.

Could you discuss toxic side effects?

We started this kind of treatment about twenty years ago. At that time we did not know the most appropriate dose for treatment field and target set up and we carried out dose escalation studies and also developed the technique for the most appropriate way to use the carbon beam. So we carry out such a dose escalation study, we experienced severe side effects in the very beginning because we escalated the dose five percent every step and then the very severe side effect occurred finally so we stopped the dose escalation.  To find out the most appropriate dose we carried out such studies, almost 50 or 60 such studies because it depends on the tumour size and disease so we need many, many such dose escalation studies. After that we overcame such a severe side effect and we found the most appropriate indication of the disease, carbon is most effective, we found.

What are the next steps in treatment?

Some patients cannot be cured even with the carbon beam, in such cases we consider much heavier particles but it causes a severe number of tissue complications expected so we set the proper target. Tumours are so heterogeneous, some parts responding very well with carbon but very tiny small parts showed a very resistant nature to the carbon. If we could identify such targets we give precisely the heavier particle to destroy the sanctuary of the tumour. That is our next step.

Any final thoughts?

X-ray can cure many cancer patients, proton too and carbon is a little bit different from x-ray or protons. Carbon could cure radio-resistant or proton-resistant tumours but the number of patients may not be so many there is some praise for carbon. There is praise of very significant roles for the best mix, cancer treatment is a best mix, many parts can be cured by x-ray and some parts with proton and some parts with carbon. So this is my conclusion, carbon can survive in the cancer treatment.