Combs Stephanie E
Department of Radiation Oncology, Technical University of Munich (TUM), Ismaninger Straße 22, 81675, Munich, Germany.
Institute of Innovative Radiotherapy (iRT), Helmholtz Zentrum München, Ingolstädter Landstraße 1, Neuherberg, Germany.
Curr Treat Options Neurol. 2017 Mar;19(3):12. doi: 10.1007/s11940-017-0447-4.
Proton therapy is characterized by certain physical properties leading to a reduction in integral dose. As proton therapy becomes more widely available, the ongoing discussion on the real indications for proton therapy becomes more important. In the present article, data on proton therapy for tumors of the central nervous system (CNS) is summarized and discussed in view of modern photon treatments. Still today, no randomized controlled trials are available confirming any clinical benefit of protons in CNS tumors. For certain skull base lesions, such as chordomas and chondrosarcomas, dose escalation is possible with protons thus patients should be referred to a proton center if readily available. For vestibular schwannoma, at present, proton data are inferior to advanced photons. For glioma patients, early data is present for low-grade gliomas, presenting comparable results to photons; dose escalation studies for high-grade gliomas have led to significant side effects, thus strategies of dose-escalation need to rethought. For skull base meningiomas, data from stereotactic series and IMRT present excellent local control with minimal side effects, thus any improvement with protons might only be marginal. The largest benefit is considered in pediatric CNS tumors, due to the intricate radiation sensitivity of children's normal tissue, as well as the potential of long-term survivorship. Long-term data is still lacking, and even recent analyses do not all lead to a clear reduction in side effects with improvement of outcome; furthermore, clinical data seem to be comparable. However, based on the preclinical evidence, proton therapy should be evaluated in every pediatric patient. Protons most likely have a benefit in terms of reduction of long-term side effects, such as neurocognitive sequelae or secondary malignancies; moreover, dose escalation can be performed in radio-resistant histologies. Clinical data with long-term follow-up is still warranted to prove any superiority to advanced photons in CNS tumors. If available, protons should be evaluated for chordoma or chondrosarcoma of the skull base and pediatric tumors. However, many factors are important for excellent oncology care, and no time delay or inferior oncological care should be accepted for the sake of protons only.
质子治疗具有某些物理特性，可使积分剂量降低。随着质子治疗的应用越来越广泛，关于质子治疗真正适应症的持续讨论变得更加重要。在本文中，鉴于现代光子治疗，对中枢神经系统（CNS）肿瘤的质子治疗数据进行了总结和讨论。时至今日，尚无随机对照试验证实质子对CNS肿瘤有任何临床益处。对于某些颅底病变，如脊索瘤和软骨肉瘤，质子治疗可实现剂量递增，因此如果条件允许，应将患者转诊至质子治疗中心。对于前庭神经鞘瘤，目前质子治疗的数据不如先进的光子治疗。对于胶质瘤患者，低级别胶质瘤有早期数据，结果与光子治疗相当；高级别胶质瘤的剂量递增研究导致了显著的副作用，因此需要重新思考剂量递增策略。对于颅底脑膜瘤，立体定向系列和调强放疗的数据显示局部控制良好且副作用最小，因此质子治疗可能仅带来微小改善。人们认为质子治疗对儿童CNS肿瘤的益处最大，这是由于儿童正常组织对辐射的敏感性复杂，以及长期生存的潜力。长期数据仍然缺乏，即使是最近的分析也并非都能明确显示随着结果改善副作用会减少；此外，临床数据似乎具有可比性。然而，基于临床前证据，应在每例儿科患者中评估质子治疗。质子治疗很可能在减少长期副作用方面有益，如神经认知后遗症或继发性恶性肿瘤；此外，对于放射抗拒的组织学类型可进行剂量递增。仍需要长期随访的临床数据来证明在CNS肿瘤方面优于先进的光子治疗。如果条件允许，应评估质子治疗用于颅底脊索瘤或软骨肉瘤以及儿科肿瘤。然而，许多因素对于优质的肿瘤治疗很重要，不应仅为了质子治疗而接受时间延迟或劣质的肿瘤治疗。
