Tensaouti Fatima, Ducassou Anne, Chaltiel Léonor, Bolle Stéphanie, Habrand Jean Louis, Alapetite Claire, Coche-Dequeant Bernard, Bernier Valérie, Claude Line, Carrie Christian, Padovani Laetitia, Muracciole Xavier, Supiot Stéphane, Huchet Aymeri, Leseur Julie, Kerr Christine, Hangard Grégorie, Lisbona Albert, Goudjil Farid, Ferrand Régis, Laprie Anne
ToNIC, Toulouse NeuroImaging Center, Universite de Toulouse, Inserm, Toulouse, France.
Department of Radiation Oncology, Institut Claudius Regaud, Institut Universitaire du, Cancer de Toulouse-Oncopole, Toulouse, France.
Front Oncol. 2019 Jun 21;9:531. doi: 10.3389/fonc.2019.00531. eCollection 2019.
Pediatric ependymoma carries a dismal prognosis, mainly owing to local relapse within RT fields. The current prospective European approach is to increase the radiation dose with a sequential hypofractionated stereotactic boost. In this study, we assessed the possibility of using a simultaneous integrated boost (SIB), comparing VMAT vs. IMPT dose delivery. The cohort included 101 patients. The dose to planning target volume (PTV59.4) was 59.4/1.8 Gy, and the dose to SIB volume (PTV67.6) was 67.6/2.05 Gy. Gross tumor volume (GTV) was defined as the tumor bed plus residual tumor, clinical target volume (CTV59.4) was GTV + 5 mm, and PTV59.4 was CTV59.4 + 3 mm. PTV67.6 was GTV+ 3 mm. After treatment plan optimization, quality indices and doses to target volume and organs at risk (OARs) were extracted and compared with the standard radiation doses that were actually delivered (median = 59.4 Gy [50.4 59.4]). In most cases, the proton treatment resulted in higher quality indices ( < 0.001). Compared with the doses that were initially delivered, mean, and maximum doses to some OARs were no higher with SIB VMAT, and significantly lower with protons ( < 0.001). In the case of posterior fossa tumor, there was a lower dose to the brainstem with protons, in terms of V59 Gy, mean, and near-maximum (D2%) doses. Dose escalation with intensity-modulated proton or photon SIB is feasible in some patients. This approach could be considered for children with unresectable residue or post-operative FLAIR abnormalities, particularly if they have supratentorial tumors. It should not be considered for infratentorial tumors encasing the brainstem or extending to the medulla.
小儿室管膜瘤预后不佳，主要原因是放疗区域内局部复发。当前欧洲的前瞻性方法是通过序贯低分割立体定向推量增加放疗剂量。在本研究中，我们评估了使用同步整合推量（SIB）的可能性，比较容积调强放疗（VMAT）与调强质子放疗（IMPT）的剂量递送情况。该队列包括101例患者。计划靶体积（PTV59.4）的剂量为59.4/1.8 Gy，SIB体积（PTV67.6）的剂量为67.6/2.05 Gy。大体肿瘤体积（GTV）定义为肿瘤床加残留肿瘤，临床靶体积（CTV59.4）为GTV + 5 mm，PTV59.4为CTV59.4 + 3 mm。PTV67.6为GTV + 3 mm。治疗计划优化后，提取质量指标以及靶体积和危及器官（OARs）的剂量，并与实际递送的标准放疗剂量进行比较（中位数 = 59.4 Gy [50.4 59.4]）。在大多数情况下，质子治疗产生的质量指标更高（<0.001）。与最初递送的剂量相比，SIB VMAT对一些OARs的平均剂量和最大剂量没有更高，而质子治疗则显著更低（<0.001）。在后颅窝肿瘤的情况下，就V59 Gy、平均剂量和近最大剂量（D2%）而言，质子治疗对脑干的剂量更低。对于一些患者，采用调强质子或光子SIB进行剂量递增是可行的。对于有不可切除残留或术后液体衰减反转恢复（FLAIR）异常的儿童，尤其是患有幕上肿瘤的儿童，可以考虑这种方法。对于包裹脑干或延伸至延髓的幕下肿瘤则不应考虑。
