Miralbell R, Bleher A, Huguenin P, Ries G, Kann R, Mirimanoff R O, Notter M, Nouet P, Bieri S, Thum P, Toussi H
Radiation Oncology Department of the University Hospital of Geneva, Switzerland.
Int J Radiat Oncol Biol Phys. 1997 Feb 1;37(3):523-9. doi: 10.1016/s0360-3016(96)00569-x.
In this study factors are analyzed that may potentially influence the site of failure in pediatric medulloblastoma. Patient-related, disease-related, and treatment-related variables are analyzed with a special focus on radiotherapy time-dose and technical factors.
Eighty-six children and adolescents with a diagnosis of medulloblastoma were treated in Switzerland during the period 1972-1991. Postoperative megavoltage radiotherapy was delivered to all patients. Simulation and portal films of the whole-brain irradiation (WBI) fields were retrospectively reviewed in 77 patients. The distance from the field margin to the cribiform plate and to the floor of the temporal fossa was carefully assessed and correlated with supratentorial failure-free survival. In 19 children the spine was treated with high-energy electron beams, the remainder with megavoltage photons. Simulation and port films of the posterior fossa fields were also reviewed in 72 patients. The field size and the field limits were evaluated and correlated with posterior fossa failure-free survival.
In 36 patients (47%) the WBI margins were judged to miss the inferior portion of the frontal and temporal lobes. Twelve patients failed in the supratentorial region and 9 of these patients belonged to the group of 36 children in whom the inferior portion of the brain had been underdosed. On multivariate analysis only field correctness was retained as being significantly correlated with supratentorial failure-free survival (p = 0.049). Neither the total dose to the spinal theca nor the treatment technique (electron vs. photon beams) were significantly correlated with outcome. Posterior fossa failure-free survival was not influenced by total dose, overall treatment time, field size, or field margin correctness. Overall survival was not influenced by any of the radiotherapy-related technical factors.
A correlation between WBI field correctness and supratentorial failure-free survival was observed. Treatment protocols should be considered that limit supratentorial irradiation mainly to subsites at highest risk of relapse. Optimized conformal therapy or proton beam therapy may help to reach this goal. Treating the spine with electron beams was not deletereous. A significant correlation between local control and other technical factors was not observed, including those relating to posterior fossa treatment. The use of small conformal tumor bed boost fields may be prefered to the larger posterior fossa fields usually considered as the standard treatment approach.
本研究分析了可能潜在影响小儿髓母细胞瘤失败部位的因素。分析了与患者、疾病及治疗相关的变量，特别关注放疗的时间剂量和技术因素。
1972年至1991年期间，瑞士对86例诊断为髓母细胞瘤的儿童和青少年进行了治疗。所有患者均接受了术后兆伏级放疗。对77例患者的全脑照射（WBI）野的模拟片和射野片进行了回顾性分析。仔细评估了射野边缘至筛板和颞窝底部的距离，并将其与幕上无瘤生存率进行了关联分析。19例儿童的脊柱采用高能电子束治疗，其余采用兆伏级光子治疗。还对72例患者的后颅窝野的模拟片和射野片进行了回顾性分析。评估了射野大小和射野边界，并将其与后颅窝无瘤生存率进行了关联分析。
36例患者（47%）的WBI边缘被判定未覆盖额叶和颞叶的下部。12例患者幕上区域复发，其中9例属于36例脑部下部剂量不足的儿童组。多因素分析显示，仅射野准确性与幕上无瘤生存率显著相关（p = 0.049）。脊髓总剂量和治疗技术（电子束与光子束）与预后均无显著相关性。后颅窝无瘤生存率不受总剂量、总治疗时间、射野大小或射野边缘准确性的影响。总生存率不受任何放疗相关技术因素的影响。
观察到WBI射野准确性与幕上无瘤生存率之间存在相关性。应考虑制定治疗方案，将幕上照射主要限制在复发风险最高的亚部位。优化的适形治疗或质子束治疗可能有助于实现这一目标。用电子束治疗脊柱并无有害影响。未观察到局部控制与其他技术因素之间存在显著相关性，包括与后颅窝治疗相关的因素。与通常被视为标准治疗方法的较大后颅窝野相比，使用小的适形瘤床加量野可能更可取。
