Barani Igor J, Cuttino Laurie W, Benedict Stanley H, Todor Dorin, Bump Edward A, Wu Yan, Chung Theodore D, Broaddus William C, Lin Peck-Sun
Department of Radiation Oncology, Virginia Commonwealth University, 401 College Street, Richmond, VA 23298, USA.
Int J Radiat Oncol Biol Phys. 2007 Jul 15;68(4):978-85. doi: 10.1016/j.ijrobp.2007.01.064. Epub 2007 Apr 30.
Recent discoveries have implicated neural stem cells (NSC) as the source of plasticity and repair in the mature mammalian brain. Treatment-induced NSC dysfunction may lead to observed toxicity. This study evaluates the feasibility of NSC-preserving external beam radiotherapy.
A single computed tomography (CT) dataset depicting a right periventricular lesion was used in this study as this location reflects the most problematic geometric arrangement with respect to NSC preservation. Conventional and NSC preserving radiotherapy (RT) plans were generated for the same lesion using two clinical scenarios: cerebral metastatic disease and primary high-grade glioma. Disease-specific target volumes were used. Metastatic disease was conventionally treated with whole-brain radiotherapy (WBRT) to 3,750 cGy (15 fractions) followed by a single stereotactic radiosurgery (SRS) boost of 1,800 cGy to gross disease only. High-grade glioma was treated with conventional opposed lateral and anterior superior oblique beams to 4,600 cGy (23 fractions) followed by a 1,400 cGy (7 fractions) boost. NSC preservation was achieved in both scenarios with inverse-planned intensity modulated radiotherapy (IMRT).
Cumulative dose reductions of 65% (metastatic disease) and 25% (high-grade glioma) to the total volume of the intracranial NSC compartments were achieved with NSC-preserving IMRT plans. The reduction of entry and exit dose to NSC niches located contralateral to the target contributed most to NSC preservation.
Neural stem cells preservation with current external beam radiotherapy techniques is achievable in context of both metastatic brain disease and high-grade glioma, even when the target is located adjacent to a stem cell compartment. Further investigation with clinical trials is warranted to evaluate whether NSC preservation will result in reduced toxicity.
最近的研究发现表明，神经干细胞（NSC）是成熟哺乳动物大脑可塑性和修复的来源。治疗引起的NSC功能障碍可能导致观察到的毒性。本研究评估保留NSC的外照射放疗的可行性。
本研究使用了一个描绘右侧脑室周围病变的计算机断层扫描（CT）数据集，因为该位置反映了在NSC保留方面最具问题的几何布局。针对同一病变，使用两种临床情况生成了传统放疗计划和保留NSC的放疗（RT）计划：脑转移瘤和原发性高级别胶质瘤。使用了疾病特异性靶区体积。脑转移瘤传统上采用全脑放疗（WBRT）至3750 cGy（15次分割），然后仅对大体病灶进行单次立体定向放射外科（SRS）增敏，剂量为1800 cGy。高级别胶质瘤采用传统的对侧水平和前上斜野放疗至4600 cGy（23次分割），然后进行1400 cGy（7次分割）的增敏。在两种情况下，通过逆向计划调强放疗（IMRT）实现了NSC的保留。
保留NSC的IMRT计划使颅内NSC区室总体积的累积剂量分别降低了65%（脑转移瘤）和25%（高级别胶质瘤）。对位于靶区对侧的NSC龛的入射和出射剂量的降低对NSC的保留贡献最大。
即使靶区位于干细胞区室附近，在脑转移瘤和高级别胶质瘤的情况下，利用当前的外照射放疗技术实现神经干细胞的保留也是可行的。有必要通过临床试验进行进一步研究，以评估保留NSC是否会降低毒性。
