Rahman Maryam, Cox J Bridger, Chi Yueh-Yun, Carter Jamal H, Friedman William A
Department of Neurosurgery, University of Florida, Gainesville, FL 32610, USA.
Stereotact Funct Neurosurg. 2012;90(2):69-78. doi: 10.1159/000334669. Epub 2012 Jan 27.
Radiographic response of brain metastasis to stereotactic radiosurgery (SRS) over time has not been well characterized. Being able to predict SRS-induced changes in tumor size over time may allow improved counseling of patients and potentially earlier recognition of poor response to SRS.
To quantify the rate of change in size of metastatic brain tumors after treatment with a linear accelerator (LINAC) SRS.
We performed a retrospective analysis of patients with single metastatic brain tumors treated with LINAC SRS at the University of Florida between 1992 and 2009 who had at least one MRI after treatment. A total of 218 patients with 406 follow-up MRI scans were included in the study. Tumor area was calculated by measuring the largest tumor area on axial imaging and using the equation for area of an ellipse. Primary outcome was percent change in tumor size. The contribution of several factors including gender, primary tumor histology, synchronous or asynchronous presentation, prior treatment, primary tumor control, and SRS dose were examined using multivariate analysis.
Mean patient age was 58.3 years (range 4-86), and 48.6% of patients were female. Sixty-three percent of patients had primary tumor control and 70.6% had asynchronous presentation of their brain metastases. SRS peripheral dose range was 1,000-2,250 cGy with a median of 1,750 cGy. The mean percent size change was -22.6% with a mean rate of change of -7.0% per month. The median percent change was -49.7% with a median rate of change of -8.8% per month. The median follow-up was 4.8 months (range 0.3-52.5). Female gender and melanoma histology were found to be significant predictors of an increase in tumor size. Lack of previous surgical resection was a significant predictor of a decrease in tumor size after SRS. Other factors tested with multivariate analysis, including age, synchronicity of presentation, dose, dose volume, Karnofsky performance score, and primary tumor control, were not significant in predicting tumor size change after SRS.
In this study, brain metastases decreased in size by a median of 50% for a median follow-up of 4.8 months after SRS. The overall rate of decrease was 9% per month after treatment with SRS. Melanoma histology was a predictor of poor tumor control.
脑转移瘤对立体定向放射外科治疗（SRS）的影像学反应随时间的变化尚未得到充分描述。能够预测SRS随时间引起的肿瘤大小变化，可能有助于更好地为患者提供咨询，并有可能更早地识别对SRS反应不佳的情况。
量化直线加速器（LINAC）SRS治疗后转移性脑肿瘤大小的变化率。
我们对1992年至2009年在佛罗里达大学接受LINAC SRS治疗的单发转移性脑肿瘤患者进行了回顾性分析，这些患者在治疗后至少有一次MRI检查。共有218例患者的406次随访MRI扫描纳入研究。通过测量轴位影像上最大的肿瘤面积并使用椭圆面积公式计算肿瘤面积。主要结局是肿瘤大小的百分比变化。使用多变量分析检查了几个因素的作用，包括性别、原发肿瘤组织学、同步或异步表现、既往治疗、原发肿瘤控制和SRS剂量。
患者平均年龄为58.3岁（范围4-86岁），48.6%的患者为女性。63%的患者原发肿瘤得到控制，70.6%的患者脑转移为异步表现。SRS外周剂量范围为1000-2250 cGy，中位数为1750 cGy。平均大小变化百分比为-22.6%，平均变化率为每月-7.0%。中位数变化百分比为-49.7%，中位数变化率为每月-8.8%。中位随访时间为4.8个月（范围0.3-52.5个月）。发现女性性别和黑色素瘤组织学是肿瘤大小增加的显著预测因素。既往未进行手术切除是SRS后肿瘤大小减小的显著预测因素。多变量分析中测试的其他因素，包括年龄、表现的同步性、剂量、剂量体积、卡氏功能状态评分和原发肿瘤控制，在预测SRS后肿瘤大小变化方面不显著。
在本研究中，SRS治疗后中位随访4.8个月时，脑转移瘤大小中位数减少50%。SRS治疗后总体减小率为每月9%。黑色素瘤组织学是肿瘤控制不佳的预测因素。
