More than 137 000 patients were treated with particle therapy worldwide from 1954 to 2014, including 15 000 in 2014, 86% of which were treated with protons and 14% with carbon ions and with other particles (Table 1). In 2014, about 10% of patients were pediatric and another 10% were treated for ocular melanomas. Forty-eight particle therapy facilities were in clinical operation at the end of 2014 (Figure 1). Two facilities in Asia (one in Lanzhou and the other in Wanjie) were temporarily shut down for technical upgrades and extensions in 2014. One facility in the United States (Indiana University Health Particle Therapy Center, Bloomington, IN) was closed down at the end of 2014 after 10 years of clinical operation. Five new particle therapy centers started patient treatments in 2014. These include two facilities in Asia (Shanghai Proton and Heavy Ion Center in Shanghai, China, and Aizawa Hospital Proton Therapy Center in Nagano, Japan) and three facilities in the United States (the Provision Center for Proton Therapy in Knoxville, TN, the Scripps Proton Therapy Center in San Diego, CA, and the Willis Knighton Proton Therapy Center in Shreveport, LA). Figure 2, Figure 3, and Figure 4 depict the number of patients treated with proton and carbon ions and their location.
At the beginning of 2015, more than 30 particle therapy centers, with a total of about 80 treatment rooms, were under construction worldwide. Half of these centers are in the United States and one-third in Asia. About 15 centers expect to start technical and/or clinical commissioning in 2015 and about half of them should be ready for patient treatment before the end of 2015.