Study on the reduction of gastrointestinal toxicity in heavy ion radiotherapy

重离子具有优越的物理剂量定位特性，因为它在体内表现出布拉格峰，并且比低let辐射（质子和光子）具有更大的生物有效性。因此，重离子有望对局部晚期放射耐药肿瘤和位于关键结构附近的肿瘤有效。然而，在不同类型的正常组织中，胃肠道对重离子表现出较高的敏感性，应被认为是腹部和盆腔肿瘤重离子治疗的关键器官。本研究的目的是调查自1994年以来在NIRS进行的碳离子治疗的急性和晚期胃肠道毒性。大多数接受治疗的患者患有局部晚期和/或医学上无法手术的肿瘤。在I/II期研究中，患者最初接受的剂量假定比正常组织可能耐受的剂量低10 ~ 20%，然后使用急性辐射发病率评分标准（RTOG）和晚期辐射发病率评分标准（RTOG/EORTC）仔细观察正常组织的反应，将剂量增加5 ~ 10%。在食管癌、宫颈癌、前列腺癌及腹部肿瘤患者的初始剂量递增试验中，对胃肠道进行部分或全部照射的患者中，有15例出现严重的晚期胃肠道并发症，其中食管2例，下肠13例。这些并发症大多发生在高剂量组，并用于评估胃肠道耐受剂量（TD）。子宫颈癌治疗引起的乙状结肠TD为57.6GyE/6周（或<62.4GyE），前列腺癌治疗引起的直肠TD为60GyE/5周（<66GyE）。食管TD分别为68.4GyE/6wks和52.8GyE/4wks。从上腹部肿瘤的治疗来看，十二指肠/胃的TD为50 ~ 60GyE/4 ~ 5wks。这些数据被充分地用于设计胰腺癌治疗的新方案，以及主要切除的直肠癌后盆腔复发。本研究结果对腹内肿瘤包括腹主动脉旁淋巴结和胆道肿瘤的治疗也有一定的指导意义。少

Heavy ions have the beneficial property of superior physical dose localization due to exhibiting the Bragg peak in the body, as well as greater biological effectiveness than low-LET radiation (protons and photons). Accordingly, heavy ions are expected to be effective against locally advanced radio-resistant tumors and those located near critical structures. Among different types of normal tissues, however, the gastro-intestinal(GI) tract exhibits high sensitivity to heavy ions and should be assumed to be a critical organ in heavy ion therapy of the abdominal and pelvic tumors. The purpose of this study was to investigate the acute and late gastrointestinal toxicity in carbon ion therapy that had been carried out since 1994 at NIRS. Most of the patients treated had locally advanced and/or medically inoperable tumors. In the phase I/II study, the patients were initially treated with the dose that was assumed to be 10〜20% lower than that possibly tolerable for the normal tissues of intere … More st. The dose was then raised by 5〜10% increments following careful observation of normal tissue responses using the acute radiation morbidity scoring criteria (RTOG) and the late radiation morbidity scoring criteria (RTOG/EORTC).Of the patients whose GI tract was partially or totally irradiated in the initial dose escalating trials for the patients with esophageal cancer, uterine cervix cancer, prostate cancer and abdominal tumors, 15 patients developed severe late GI complications : 2 patients in the esophagus, 13 patients in the lower bowels. Most of these complications were observed in the high dose groups, and were served for evaluation of tolerable dose(TD) of the GI tract. The TD derived from treatment of uterine cervix cancer was 57.6GyE/6 wks (or <62.4GyE) for the sigmoid colon and from treatment of prostate cancer it was 60GyE/5 wks (<66GyE) for the rectum. The TD of the esophagus was 68.4GyE/6wks or 52.8GyE/4wks. From treatment of upper abdominal tumors, the TD of the duodenum/stomach was derived to be 50〜60GyE/4〜5wks. These data were sufficiently utilized for designing new protocols for treatment of pancreatic cancer as well as pelvic recurrence after primarily resected rectal cancer. The results of the current study will be also useful for treatment of intra-abdominal tumors including the para-aortic lymph nodes and biliary tract tumors. Less