Carbon Ion Radiotherapy - Chiba Experience

Carbon ion radiotherapy (CIRT) is a unique radiotherapy, which possesses well localized and superior depth dose distribution in addition to uniform, less repairable radiobiological effects. The use of CIRT for various diseases has been explored as clinical trials at the Heavy Ion Medical Accelerator in Chiba (HIMAC), Japan, since 1994. From June 1994 to February 2009, a total of 4,503 patients were enrolled into clinical studies using carbon beams. We treated almost 700 new patients per year in 2008. Lung, head and neck, prostate, liver and bone and soft tissue sarcomas are the leading 5 tumors in our studies. 1) Head and Neck. More than 500 locally advanced tumors were treated in head and neck protocols. Two dose-escalating protocols were carried out and then a fixed 16 fractions over 4 weeks study was conducted. In these studies, non-squamous cell cancers such as malignant melanoma, adenoid cystic carcinoma and adeno-carcinoma, those considered to be radio-resistant, showed better outcomes. 2) Lung cancer. Patients with medically inoperable stage I non small cell cancer were treated in several protocols. We started with a fixed 18 fractions over 6 weeks dose-escalating study, and then shortened the overall treatment time to 3 weeks in 3 protocols. The results of these studies are better than those of conventional radiotherapy, and almost the same as those of surgery. We have conducted a fixed 4 fractions over one week protocol since 2000. We could give a very high dose in a week without unacceptable side effects. A single fraction dose-escalating study was started in 2003. 3) Liver Cancer. For liver cancer, a 15 fixed fractions over 5 weeks dose escalating protocol was carried out initially. Overall treatment time of 5 weeks then was shortened to 3, 2 and 1 week in the following protocol. The results were more than expectations. We have conducted a fixed 2 fractions dose escalating protocol since 2003. 4) Prostate Cancer. At first, a fixed 20 fractions over 5 weeks protocol was employed, a total dose of 63 GyE was found to be an optimal dose. Overall treatment time was then shortened to 4 weeks, showed better outcomes. 5) Bone and Soft Tissue Sarcomas (BSTSs). BSTSs are one of the most radio-resistant tumors. More than 450 unresectable tumors were treated with fixed 16 fractions over 4-week protocols. According to the results, CIRT could offer a survival advantage without unacceptable morbidity in sarcoma.Our experience to date is summarized as follows: CIRT is effective especially (1) in regions such as the head and neck, skull base, lung, liver, prostate, bone and soft tissue, and the pelvic recurrence of rectal cancer and (2) for histological types such as non-squamous cell cancers and sarcomas. It is emphasized that (3) the short course hypo-fractionated regimen was effective against various tumors by using the advantages of biological dose distributionHeavy Ions in Therapy and Space Symposium 200