Section of Radiation Oncology, Department of Radiology, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03756-0001, USA.
Int J Radiat Oncol Biol Phys. 2012 Nov 15;84(4):943-8. doi: 10.1016/j.ijrobp.2012.01.067. Epub 2012 Apr 9.
To analyze 2 factors that influence timing of radiosurgery after surgical resection of brain metastases: target volume dynamics and intracranial tumor progression in the interval between surgery and cavity stereotactic radiosurgery (SRS).
Three diagnostic magnetic resonance imaging (MRI) scans were retrospectively analyzed for 41 patients with a total of 43 resected brain metastases: preoperative MRI scan (MRI-1), MRI scan within 24 hours after surgery (MRI-2), and MRI scan for radiosurgery planning, which is generally performed ≤1 week before SRS (MRI-3). Tumors were contoured on MRI-1 scans, and resection cavities were contoured on MRI-2 and MRI-3 scans.
The mean tumor volume before surgery was 14.23 cm3, and the mean cavity volume was 8.53 cm3 immediately after surgery and 8.77 cm3 before SRS. In the interval between surgery and SRS, 20 cavities (46.5%) were stable in size, defined as a change of ≤2 cm3; 10 cavities (23.3%) collapsed by >2 cm3; and 13 cavities (30.2%) increased by >2 cm3. The unexpected increase in cavity size was a result of local progression (2 cavities), accumulation of cyst-like fluid or blood (9 cavities), and nonspecific postsurgical changes (2 cavities). Finally, in the interval between surgery and SRS, 5 cavities showed definite local tumor progression, 4 patients had progression elsewhere in the brain, 1 patient had both local progression and progression elsewhere, and 33 patients had stable intracranial disease.
In the interval between surgical resection and delivery of SRS, surgical cavities are dynamic in size; however, most cavities do not collapse, and nearly one-third are larger at the time of SRS. These observations support obtaining imaging for radiosurgery planning as close to SRS delivery as possible and suggest that delaying SRS after surgery does not offer the benefit of cavity collapse in most patients. A prospective, multi-institutional trial will provide more guidance to the optimal timing of cavity SRS.
分析影响脑转移瘤手术后立体定向放射外科（SRS）治疗时间的 2 个因素：手术和立体定向放射外科治疗前的手术切除腔之间的目标体积动态和颅内肿瘤进展。
对 41 例共 43 个脑转移瘤患者的 3 次诊断性磁共振成像（MRI）扫描进行回顾性分析：术前 MRI 扫描（MRI-1）、手术后 24 小时内的 MRI 扫描（MRI-2）以及放射外科治疗计划的 MRI 扫描，通常在 SRS 前≤1 周进行（MRI-3）。在 MRI-1 扫描上勾画肿瘤，在 MRI-2 和 MRI-3 扫描上勾画切除腔。
术前肿瘤平均体积为 14.23cm3，术后即刻切除腔平均体积为 8.53cm3，SRS 前为 8.77cm3。在手术和 SRS 之间的间隔内，20 个切除腔（46.5%）大小稳定，定义为变化≤2cm3；10 个切除腔（23.3%）塌陷>2cm3；13 个切除腔（30.2%）增大>2cm3。切除腔大小的意外增大是局部进展（2 个切除腔）、囊性或血性积液积聚（9 个切除腔）和非特异性术后改变（2 个切除腔）的结果。最后，在手术和 SRS 之间的间隔内，5 个切除腔显示明确的局部肿瘤进展，4 例患者脑内其他部位进展，1 例患者局部和其他部位均进展，33 例患者颅内疾病稳定。
在手术切除和 SRS 治疗之间的间隔内，手术切除腔的大小是动态的；然而，大多数切除腔没有塌陷，在 SRS 治疗时近三分之一的切除腔更大。这些观察结果支持尽可能接近 SRS 治疗进行放射外科治疗计划的影像学检查，并表明大多数患者手术后延迟 SRS 治疗并不能带来切除腔塌陷的益处。一项前瞻性、多机构试验将为最佳切除腔 SRS 时机提供更多指导。
