Department of Human Oncology, University of Wisconsin, Madison, WI 53792, USA.
Int J Radiat Oncol Biol Phys. 2013 Feb 1;85(2):348-54. doi: 10.1016/j.ijrobp.2012.11.031.
To prospectively evaluate the association between hippocampal dose and long-term neurocognitive function (NCF) impairment for benign or low-grade adult brain tumors treated with fractionated stereotactic radiotherapy (FSRT).
Adult patients with benign or low-grade adult brain tumors were treated with FSRT per institutional practice. No attempt was made to spare the hippocampus. NCF testing was conducted at baseline and 18 months follow-up, on a prospective clinical trial. Regression-based standardized z scores were calculated by using similar healthy control individuals evaluated at the same test-retest interval. NCF impairment was defined as a z score ≤-1.5. After delineation of the bilateral hippocampi according to the Radiation Therapy Oncology Group contouring atlas, dose-volume histograms were generated for the left and right hippocampi and for the composite pair. Biologically equivalent doses in 2-Gy fractions (EQD(2)) assuming an α/β ratio of 2 Gy were computed. Fisher's exact test and binary logistic regression were used for univariate and multivariate analyses, respectively. Dose-response data were fit to a nonlinear model.
Of 29 patients enrolled in this trial, 18 completed both baseline and 18-month NCF testing. An EQD(2) to 40% of the bilateral hippocampi >7.3 Gy was associated with impairment in Wechsler Memory Scale-III Word List (WMS-WL) delayed recall (odds ratio [OR] 19.3; p = 0.043). The association between WMS-WL delayed recall and EQD(2) to 100% of the bilateral hippocampi >0.0 Gy trended to significance (OR 14.8; p = 0.068).
EQD(2) to 40% of the bilateral hippocampi greater than 7.3 Gy is associated with long-term impairment in list-learning delayed recall after FSRT for benign or low-grade adult brain tumors. Given that modern intensity-modulated radiotherapy techniques can reduce the dose to the bilateral hippocampi below this dosimetric threshold, patients should be enrolled in ongoing prospective trials of hippocampal sparing during cranial irradiation to confirm these preliminary results.
前瞻性评估接受分割立体定向放疗（FSRT）治疗的良性或低级别成人脑肿瘤患者海马剂量与长期神经认知功能（NCF）损害之间的关系。
按照机构惯例，对患有良性或低级别成人脑肿瘤的成年患者进行 FSRT 治疗。未尝试保留海马体。在一项前瞻性临床试验中，于基线和 18 个月随访时进行 NCF 测试。使用在相同测试-重测间隔内评估的相似健康对照个体，通过基于回归的标准化 z 分数进行计算。将 z 分数≤-1.5 定义为 NCF 损害。根据放射治疗肿瘤学组（RTOG）轮廓图谱描绘双侧海马体后，生成左、右海马体和复合对的剂量-体积直方图。根据假设 α/β 比为 2 Gy 的 2 Gy 等效剂量（EQD(2)）进行计算。Fisher 确切检验和二元逻辑回归分别用于单变量和多变量分析。剂量反应数据拟合到非线性模型中。
在这项试验中，29 名患者入组，其中 18 名患者完成了基线和 18 个月的 NCF 测试。双侧海马体 40%的 EQD(2)＞7.3 Gy 与韦氏记忆量表-III 单词列表（WMS-WL）延迟回忆受损相关（优势比 [OR] 19.3；p = 0.043）。WMS-WL 延迟回忆与双侧海马体 100%的 EQD(2)＞0.0 Gy 之间的关联呈显著趋势（OR 14.8；p = 0.068）。
双侧海马体 40%的 EQD(2)大于 7.3 Gy 与接受 FSRT 治疗的良性或低级别成人脑肿瘤后长期列表学习延迟回忆受损相关。鉴于现代调强放疗技术可以将双侧海马体的剂量降低到这个剂量学阈值以下，因此应该让患者参与正在进行的颅照射中保留海马体的前瞻性试验，以确认这些初步结果。
