In 1994,
carbon-ion radiotherapy was started at the National Institute of Radiological Sciences using the Heavy-Ion Medical Accelerator in Chiba. Between June 1995 and March 2000, two phase I/II dose escalation studies (protocols 9402 and 9703) of hypofractionated
carbon-ion radiotherapy for both early- and advance-stage
prostate cancer patients had been carried out to establish
radiotherapy technique and to determine the optimal radiation dose. To validate the feasibility and efficacy of hypofractionated
carbon-ion radiotherapy, a phase II study (9904) was initiated in April 2000 using the shrinking field technique and the recommended dose fractionation (66 gray equivalents in 20 fractions over 5 weeks) obtained from the phase I/II studies, and was successfully completed in October 2003. The data from 175 patients in the phase II study showed the importance of an appropriate use of
androgen deprivation
therapy according to
tumor risk group. Since November 2003,
carbon-ion radiotherapy for
prostate cancer was approved as "Highly Advanced Medical Technology" from the Ministry of Health, Labor, and Welfare, and since then approximately 1100 patients have received
carbon-ion radiotherapy as of July 2011. In this review, we introduce our steps thorough three clinical trials carried out at National Institute of Radiological Sciences, and show the updated data of
carbon-ion radiotherapy obtained from approximately 1000
prostate cancer patients. In addition, our recent challenge and future direction will be also described.