[Initial experience of proton beam therapy at the new facility of the University of Tsukuba].

To present the initial experience with proton beam therapy at the new Proton Medical Research Center (PMRC) of the University of Tsukuba.The new facility has a synchrotron with maximum energy of 250MeV and two rotational gantries. We treated 105 patients with 120 lesions with proton beams in the first year, beginning in September 2001. The most common lesion treated was primary liver cancer (40 lesions) followed by lung cancer, head and neck cancers, and prostate cancer. Concurrent X-ray radiotherapy was given for 38 of the 120 lesions.The median follow-up period was 11 months (range, 1-19 months). Of the 105 patients, 97% had Grade 0-2 RTOG/EORTC acute morbidities, while the remaining 3% had Grade 3. Tumor response after irradiation was CR for 35% of the lesions, PR for 25%, SD for 22%, PD for 9%, and not evaluated for 9%.The proton beam therapy conducted at the new facility of the University of Tsukuba was safe and effective.