Department of Radiation Oncology, Weill Cornell Medical College, New York Presbyterian-Brooklyn Methodist Hospital, Brooklyn, New York.
Center for Neuro-Oncology, Dana-Farber/Brigham and Women's Cancer Center, Harvard Medical School, Boston, Massachusetts.
Neuro Oncol. 2019 May 6;21(5):640-647. doi: 10.1093/neuonc/noz023.
Whole-brain radiotherapy (WBRT) in patients with brain metastases (BM) is associated with neurocognitive decline. Given its crucial role in learning and memory, efforts to mitigate this toxicity have mostly focused on sparing radiation to the hippocampus. We hypothesized that BM are not evenly distributed across the brain and that several additional areas may be avoided in WBRT based on a low risk of developing BM.
We contoured 2757 lesions in a large, single-institution database of patients with newly diagnosed BM. BM centroids were mapped onto a standard brain atlas of 55 anatomic subunits and the observed percentage of BM was compared with what would be expected based on that region's volume. A region of interest (ROI) analysis was performed in a validation cohort of patients from 2 independent institutions using equivalence and one-sample hypothesis tests.
The brainstem and bilateral thalami, hippocampi, parahippocampal gyri, amygdala, and temporal poles had a cumulative risk of harboring a BM centroid of 4.83% in the initial cohort. This ROI was tested in 157 patients from the validation cohort and was found to have a 4.1% risk of developing BM, which was statistically equivalent between the 2 groups (P < 1 × 10-6, upper bound).
Several critical brain structures are at a low risk of developing BM. A risk-adapted approach to WBRT is worthy of further investigation and may mitigate the toxicities of conventional radiation.
脑转移瘤（BM）患者的全脑放疗（WBRT）与神经认知功能下降有关。鉴于其在学习和记忆中的关键作用，减轻这种毒性的努力主要集中在避免放射对海马体的损伤。我们假设，BM 在大脑中的分布并不均匀，根据发生 BM 的低风险，WBRT 可以避免几个其他的额外区域。
我们对一个大型单机构 BM 患者数据库中的 2757 个病灶进行了勾画。BM 中心点被映射到 55 个解剖亚区的标准大脑图谱上，并将观察到的 BM 百分比与该区域体积的预期百分比进行比较。在来自 2 个独立机构的患者的验证队列中，使用等效性和单样本假设检验进行了 ROI 分析。
在初始队列中，脑干和双侧丘脑、海马体、海马旁回、杏仁核和颞极累积存在 BM 中心点的风险为 4.83%。该 ROI 在验证队列中的 157 名患者中进行了测试，发现发生 BM 的风险为 4.1%，两组之间的统计学上无差异（P < 1 × 10-6，上限）。
几个关键的大脑结构发生 BM 的风险较低。风险适应性 WBRT 方法值得进一步研究，并可能减轻常规放疗的毒性。
