Ten Years Experience of Carbon Ion Radiotherapy for Prostate

Purposes : To evaluate the usefulness of carbon ion beams in the treatment of prostate cancer by analyzing the Results : of 3 institutional clinical trialsMaterials and Methods: A total of 432 patients were enrolled to three consecutive trials of C-ion RT for prostate cancer between Jun.1995 and Feb.2006. Analysis was performed on 378 patients who had the histological diagnosis of central pathologist and a follow-up period of more than 6 months. The C-ion RT of 20 fractions over 5weeks was carried out for all the patients and the applied doses ranged from 54.0GyE to 72.0GyE according to the dose-escalation protocol performed in the first two studies. Three hundreds and three (80%) of the patients received 66.0GyE/20fr. mostly in the third trial. Androgen deprivation (AD) was applied to the patient with relatively high risk factors (HR), such as PSA > or = 20ng/ml or T-stage > or = T2b or Gleason score (GS) > or = 7. Neoadjuvant AD was administrated for 2 - 6 months before the C-ion RT and adjuvant AD was given for at least 12 months except for the HR patients with pathological evidence of N0 (pN0). The patient with lower risk factors (LR), such as PSA or = 20, and the median value was 18.0. Centrally reviewed Gleason score was or = 8 in 98 patients, respectively. Out of the 378 patients, 62 were categorized to the LR and the remaining 316 were HR.Eight patients treated in the first dose-escalation study developed grade III late radiation morbidities in the rectum or the genitourinary system (GU). The applied dose and radiation techniques were modified according to the dose-volume histogram analysis using the results of this study and no grade III morbidity has observed after these modifications. With the current method of C-ion RT, grade II morbidities occurred only 2.1% patients in the rectum and 7.0% in the GU. Kaplan-Meier estimates of overall and cause-specific survival (CSS) rates at 5 and 8 years were 90.5%, 77.7% and 97.5%, 97.5%, respectively.Biochemical relapse free rates (BRF) at 5 and 8 years were 87.7% and 81.8%, respectively. The BRF of the HR and LR groups at 8 years were 80.5% and 90.9%, respectively, but the difference was not statistically significant. Concerning the influence of each risk factor on the BRF or CSS, T-stage and GS had significant influences on both endpoints but PSA did not. Conclusion: Through the 3 clinical trials, the sufficiently safe and effective treatment methods of C-ion RT for prostate cancer could be established. Recently, the intermediate risk group was separated from the HR group and shortening the duration of AD for this group for the sake of improvement of patient\u27s QOL