Schild Steven E, Sio Terence T, Daniels Thomas B, Chun Stephen G, Rades Dirk
Mayo Clinic, Scottsdale, AZ; University of Texas MD Anderson Cancer Center, Houston, TX; and University of Lübeck, Lübeck, Germany.
J Oncol Pract. 2017 Nov;13(11):732-738. doi: 10.1200/JOP.2017.026765.
Small-cell lung cancer (SCLC) has a high predilection for metastasizing to the brain after chemotherapy. This has been blamed on the blood-brain barrier, which prevents chemotherapy from penetrating into the brain, thus creating a sanctuary site. It has been estimated that up to three quarters of patients with SCLC will eventually develop brain metastases. This led investigators to administer prophylactic cranial irradiation (PCI) to decrease this risk. Several trials were performed in patients with SCLC after initial therapy (chemotherapy with or without thoracic radiotherapy) that compared the outcomes of PCI versus no PCI. Early trials generally found that PCI significantly decreased the risk of brain metastases but did not significantly improve survival. These trials were re-evaluated in two larger meta-analyses that included patients with either limited-stage SCLC or extensive-stage SCLC (ESCLC). Both meta-analyses reported that PCI significantly decreased brain metastases and improved survival in patients who had a complete response following initial therapy. These studies were performed before the advent of modern imaging with computed tomography or magnetic resonance imaging (MRI). There have been two modern trials of PCI versus no PCI in patients with ESCLC and both found that PCI decreases brain metastases. The first did not include brain MRI before registration and found that PCI improved survival, whereas the second study did include MRI before registration and at frequent intervals thereafter. That trial found that PCI did not confer a survival advantage. This review will examine the evidence and provide recommendations regarding the role of PCI for patients with ESCLC.
小细胞肺癌（SCLC）在化疗后极易发生脑转移。这被归咎于血脑屏障，它阻止化疗药物进入大脑，从而形成一个庇护所部位。据估计，高达四分之三的SCLC患者最终会发生脑转移。这促使研究人员进行预防性颅脑照射（PCI）以降低这种风险。在SCLC患者接受初始治疗（化疗加或不加胸部放疗）后进行了多项试验，比较了PCI与不进行PCI的结果。早期试验通常发现，PCI显著降低了脑转移的风险，但并未显著提高生存率。在两项更大规模的荟萃分析中对这些试验进行了重新评估，这些荟萃分析纳入了局限期SCLC或广泛期SCLC（ESCLC）患者。两项荟萃分析均报告称，PCI显著降低了脑转移风险，并改善了初始治疗后完全缓解患者的生存率。这些研究是在计算机断层扫描或磁共振成像（MRI）等现代成像技术出现之前进行的。在ESCLC患者中进行了两项关于PCI与不进行PCI的现代试验，两者均发现PCI可降低脑转移。第一项试验在登记前未进行脑部MRI检查，发现PCI可提高生存率，而第二项研究在登记前及此后频繁进行MRI检查。该试验发现PCI没有生存优势。本综述将审查相关证据，并就PCI对ESCLC患者的作用提供建议。
