Department of Radiation Oncology, Rush University Medical Center, Chicago, Illinois, USA.
Int J Radiat Oncol Biol Phys. 2010 Feb 1;76(2):504-12. doi: 10.1016/j.ijrobp.2009.02.038.
We report the incidence of metastatic involvement of the limbic circuit in a retrospective review of patients treated at our institution. This review was performed to assess the feasibility of selectively sparing the limbic system during whole-brain radiotherapy and prophylactic cranial irradiation.
We identified 697 intracranial metastases in 107 patients after reviewing contrast-enhanced CT and/or MR image sets for each patient. Lesions were localized to the limbic circuit or to the rest of the brain/brain stem. Patients were categorized by tumor histology (e.g., non-small-cell lung cancer, small-cell lung cancer, breast cancer, and other) and by total number of intracranial metastases (1-3, oligometastatic; 4 or more, nonoligometastatic).
Thirty-six limbic metastases (5.2% of all metastases) were identified in 22 patients who had a median of 16.5 metastases/patient (limbic metastases accounted for 9.9% of their lesions). Sixteen metastases (2.29%) involved the hippocampus, and 20 (2.86%) involved the rest of the limbic circuit; 86.2% of limbic metastases occurred in nonoligometastatic patients, and 13.8% occurred in oligometastatic patients. The incidence of limbic metastases by histologic subtype was similar. The incidence of limbic metastases in oligometastatic patients was 4.9% (5/103): 0.97%, hippocampus; 3.9%, remainder of the limbic circuit. One of 53 oligometastatic patients (1.9%) had hippocampal metastases, while 4/53 (7.5%) had other limbic metastases.
Metastatic involvement of the limbic circuit is uncommon and limited primarily to patients with nonoligometastatic disease, supporting our hypothesis that it is reasonable to selectively exclude or reduce the dose to the limbic circuit when treating patients with prophylactic cranial irradiation or whole-brain radiotherapy for oligometastatic disease not involving these structures.
我们通过回顾在我院治疗的患者，报告边缘系统回路转移的发生率。进行这项回顾是为了评估在全脑放疗和预防性颅脑照射过程中选择性保留边缘系统的可行性。
我们通过对比增强 CT 和/或磁共振图像对 107 名患者的图像集进行回顾，共确定了 697 例颅内转移。病变定位于边缘系统回路或脑/脑干的其他部位。患者根据肿瘤组织学（例如非小细胞肺癌、小细胞肺癌、乳腺癌和其他）和颅内转移总数（1-3 个，寡转移；4 个或更多，非寡转移）进行分类。
22 名患者（占所有转移患者的 5.2%）共发现 36 个边缘转移（22 名患者的中位数为 16.5 个转移/患者，边缘转移占其病变的 9.9%）。16 个转移（2.29%）累及海马体，20 个（2.86%）累及边缘系统的其他部位；86.2%的边缘转移发生在非寡转移患者中，13.8%发生在寡转移患者中。根据组织学亚型，边缘转移的发生率相似。寡转移患者的边缘转移发生率为 4.9%（5/103）：0.97%，海马体；3.9%，边缘系统的其余部分。53 例寡转移患者中仅有 1 例（1.9%）有海马转移，而 53 例中有 4 例（7.5%）有其他边缘转移。
边缘系统回路的转移并不常见，主要局限于非寡转移疾病患者，这支持了我们的假设，即在治疗不涉及这些结构的寡转移疾病患者的预防性颅脑照射或全脑放疗时，选择性排除或减少边缘系统的剂量是合理的。
