Inakoshi Hideki, Kayamori Ryo, Tsuchida Emiko, Sakai Kunio, Shibamoto Yuta, Wakushima Hiroshi, Ogawa Yoshihiro, Kobayashi Mitsuru, Obara Toya
Department of Radiological Technology, Niigata University School of Health Sciences, Japan.
Radiat Med. 2003 Jan-Feb;21(1):37-45.
To examine in retrospect prognostic factors influencing meningeal dissemination relapse of medulloblastoma (MB) and to estimate time parameter gamma/alpha of the biologically effective dose for fractionated craniospinal irradiation (CSI).
Fifty-eight patients with MB who had been treated at our six hospitals from 1980 to 1990, were analyzed by the proportional hazards model consisting of radiation factors of both CSI and local irradiation (LI), sequential CSI time-lag, and eight non-radiation factors (gender, age, performance status, T-stage, dissemination score, extent of resection, and use of chemotherapy and immunotherapy). The gamma/alpha for CSI was estimated by the profile likelihood method using the maximum value of conditionally calculated time-incorporated biologically effective dose, tBEDmax, of the field treated with the least dose.
Dissemination relapse was seen in 23 (40%) patients. Nineteen disseminations occurred within four years, and the cumulative dissemination-free rate was 64% at five years. The site of initial dissemination relapse was both cranial and spinal in 13 patients (57%). Dissemination relapse was accompanied with local failure in 43% (10/23) of patients, and four of them were seen later than four years. In the multivariate analysis, significant prognostic factors were dissemination score (p=0.0008) and total dose of CSI (p=0.018). The estimate of gamma/alpha for CSI was about 0.2 Gy/day in BED units. In another multivariate analysis including the best-fitted tBEDmax, significant prognostic factors were dissemination score and the tBEDmax of both CSI (p=0.021) and LI (p=0.024).
This analysis indicated that the dissemination score, total dose of CSI, and tBEDmax of both CSI and LI were significantly prognostic for dissemination relapse of MB. The estimate of gamma/alpha for CSI was smaller than that derived from our previous analysis for LI. However, in order to estimate the time factor for CSI more precisely, a larger group of patients treated with concurrent CSI is needed.
回顾性研究影响髓母细胞瘤（MB）脑膜播散复发的预后因素，并估算分次全脑全脊髓照射（CSI）生物等效剂量的时间参数γ/α。
对1980年至1990年在我们六家医院接受治疗的58例MB患者进行分析，采用比例风险模型，该模型包括CSI和局部照射（LI）的放疗因素、连续CSI时间延迟以及八个非放疗因素（性别、年龄、体能状态、T分期、播散评分、切除范围以及化疗和免疫治疗的使用情况）。通过轮廓似然法，利用接受最低剂量照射野的条件性计算的含时间生物等效剂量（tBEDmax）的最大值来估算CSI的γ/α。
23例（40%）患者出现播散复发。19例在四年内发生播散，五年时累积无播散率为64%。13例患者（57%）的初始播散复发部位包括颅脑和脊髓。43%（10/23）的患者播散复发伴有局部失败，其中4例发生在四年以后。多因素分析中，显著的预后因素为播散评分（p = 0.0008）和CSI总剂量（p = 0.018）。以BED为单位，CSI的γ/α估计约为0.2 Gy/天。在另一项包括最佳拟合tBEDmax的多因素分析中，显著的预后因素为播散评分以及CSI（p = 0.021）和LI（p = 0.024）的tBEDmax。
该分析表明，播散评分、CSI总剂量以及CSI和LI的tBEDmax对MB的播散复发具有显著的预后意义。CSI的γ/α估计值低于我们之前对LI分析得出的值。然而，为了更精确地估算CSI的时间因素，需要更大一组接受同步CSI治疗的患者。
