Most stage IV cancer patients present with widely disseminated disease.¹ In these patients, painful bone metastases, or those at risk of neurological compromise, warrant palliative radiotherapy (with or without surgery), before commencing systemic therapy. Palliative conventional external beam radiotherapy (cEBRT) to bone (including spine) metastases is typically of low doses, ranging from 8 Gy in a single fraction (equivalent dose in 2 Gy equivalent [EQD2] 12 Gy) to 30 Gy in 10 fractions (EQD2 32.5 Gy). These regimens provide an adequate pain relief for the majority of patients.² Patients with “good tumor biology” remain controlled with systemic therapy for a period of time. However, radio-resistant and chemo-resistant clones eventually emerge, resulting in locally recurrent disease. These may be symptomatic or detected on radiological surveillance. In this scenario, reirradiation of the same lesion involves complex decision-making and treatment planning calculations. The expected repair of sublethal damage in the adjacent organs from the prior course of radiation also needs to be considered. However, it may not be optimal to re-treat the lesion with a lower dose of radiation than the first course. These sites have proven themselves to be resistant, and a lower dose of radiotherapy will certainly not provide adequate local control.³

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评论：成熟的基于影像学的结果支持复杂再辐射的局部控制挽救脊柱立体定向身体放射疗法。

大多数IV期癌症患者表现出广泛传播的疾病。¹在这些患者中，疼痛的骨转移瘤或有神经功能受损风险的患者，应在开始全身治疗之前进行姑息性放疗（有或没有手术）。对骨（包括脊柱）转移瘤的姑息性常规外束放射疗法（cEBRT）通常剂量较低，范围从单份8 Gy（等效于2 Gy当量[EQD2] 12 Gy的等效剂量）到10馏分30 E（DQD2） 32.5 Gy）。这些方案为大多数患者提供了足够的疼痛缓解。²具有“良好肿瘤生物学”的患者在一段时间内仍可通过全身治疗得到控制。但是，最终出现了耐辐射和耐化学性的克隆，导致局部复发。这些可能是有症状的，也可能是在放射学监测中发现的。在这种情况下，对同一病变进行重新照射涉及复杂的决策和治疗计划计算。还需要考虑到先前辐射对邻近器官的亚致死损伤的预期修复。但是，以比第一疗程低的放射剂量重新治疗病灶可能不是最佳的。这些部位已被证明具有抵抗力，并且较低剂量的放射治疗当然不能提供足够的局部控制。³