Epidemiological Study of the Incidence of Cancers Eligible for Proton or Carbon Ions Therapy: Methodology and Results of Recruitment Estimation

Context. Hadrontherapy is an innovative form of radiotherapy using beams of protons or carbon ions able to destroy some radio-resistant tumours. Because these tumours are highly specific amongst all cancerous tumours, it is impossible to determine the incidence of these diseases from surveillance registries. Goal. To assess, within the Rh？ne-Alpes region, the incidence of cancers being hadrontherapy indications. Method. Prospective, multicentre continuous data collection during 1 year, by practitioners participating to multidisciplinary tumor board. Tumours are inoperable, radio resistant, at primary stage of development, or locally recurrent, with low metastatic potential. Results. Study involved 27 healthcare centres, 52 groups of specialist practitioners. The estimated incidence of cancers eligible for hadrontherapy in the Rh？ne-Alpes region in 2010, that is, for 34 locations in all, is of 8.5/100？000 inhabitants. Appraisal of the low potential of metastatic progression is impeded, because these are rare diseases, whose outcome is unfamiliar to investigators. Conclusion. Future epidemiological studies will need to focus on prognosis and on the metastatic progression rate of these diseases. Indeed, there are few information available on this subject in the literature that could be used to improve preventive measures, medical care, and the surveillance of these rare cancers. 1. Scientific Context 1.1. Hadrontherapy Hadrontherapy is an innovative form of radiotherapy, based on high-technology equipment using proton or carbon ions beams to destroy tumours [1, 2]. This treatment method enables significantly higher ballistic precision to be achieved, compared to photons (X-rays) with, as expected therapeutic benefit, an improvement of quality of life and chances of recovery [3]. Carbon ions are also specifically characterised by superior biological efficacy (relative biological effectiveness from 1.5 to 3), overcoming the radiation resistance of certain cancers to photons and even protons. Indeed, carbon ion beams when compared to X-rays represent a distinct advantage for the treatment of highly radiation-resistant tumours [4]. 1.2. Hadrontherapy Epidemiological Studies An initial study assessing recruitment potential for proton therapy was conducted in 1998 in Italy, showing an incidence of 10？825 cases/year [5]. One year later, a second study was carried out in the context of the MedAustron project for the construction of a carbon ions therapy centre in Austria. Considering patients living in Austria and neighbouring countries, the patient recruitment