Department of Internal Medicine, University of Manitoba.
Departments of Hematology and Medical Oncology.
Am J Clin Oncol. 2021 Dec 1;44(12):629-638. doi: 10.1097/COC.0000000000000867.
Central nervous system (CNS) metastasis will develop in 50% of small cell lung cancer (SCLC) patients throughout disease course. Development of CNS metastasis poses a particular treatment dilemma due to the accompanied cognitive changes, poor permeability of the blood-brain barrier to systemic therapy and relatively advanced state of disease. Survival of patients with untreated SCLC brain metastases is generally <3 months with whole brain radiotherapy used as first-line management in most SCLC patients. To prevent development of CNS metastasis prophylactic cranial irradiation (PCI) is recommended in limited stage disease, after response to chemotherapy and radiation, while PCI may be considered in extensive stage disease after favorable response to upfront treatment. Neurocognitive toxicity with whole brain radiotherapy and PCI is a concern and remains difficult to predict. The mechanism of toxicity is likely multifactorial, but a potential mechanism of injury to the hippocampus has led to hippocampal sparing radiation techniques. Treatment of established non-small cell lung cancer CNS metastases has increasingly focused on using stereotactic radiotherapy (SRS) and it is tempting to extrapolate these results to SCLC. In this review, we explore the evidence surrounding the prediction, prevention, detection, and treatment of CNS metastases in SCLC. We further review whether existing evidence supports extrapolating less toxic treatments to SCLC patients with CNS metastases and discuss trials that may shed more light on this question.
中枢神经系统（CNS）转移将在小细胞肺癌（SCLC）患者的疾病过程中发展 50%。由于认知功能的改变、全身治疗对血脑屏障的通透性差以及疾病的相对晚期状态，CNS 转移的发展带来了特殊的治疗困境。未经治疗的 SCLC 脑转移患者的生存时间一般<3 个月，大多数 SCLC 患者的一线治疗方法是全脑放疗。为了预防 CNS 转移，有限期疾病在化疗和放疗后缓解时建议预防性颅照射（PCI），而广泛期疾病在初始治疗后反应良好时也可以考虑 PCI。全脑放疗和 PCI 的神经认知毒性是一个令人关注的问题，且仍然难以预测。毒性的机制可能是多因素的，但海马损伤的潜在机制导致了海马保护放射技术。治疗已确诊的非小细胞肺癌 CNS 转移越来越关注使用立体定向放疗（SRS），并试图将这些结果外推至 SCLC。在这篇综述中，我们探讨了 SCLC 中 CNS 转移的预测、预防、检测和治疗方面的证据。我们进一步探讨了是否有现有证据支持将毒性较小的治疗方法外推到患有 CNS 转移的 SCLC 患者，并讨论了可能有助于回答这个问题的试验。
