Gamma Knife of Spokane, Spokane, Washington, USA.
World Neurosurg. 2011 May-Jun;75(5-6):673-83. doi: 10.1016/j.wneu.2010.12.006.
Stereotactic radiosurgery (SRS) is a form of radiation therapy that delivers a focused, highly conformal dose of radiation to a single volume, while minimizing damage to the adjacent nervous tissue. The efficacy of SRS has been examined in the treatment of patients diagnosed with brain metastases due to the fact that it is capable of targeting any region in the brain and can irradiate multiple tumors in the same treatment setting in a noninvasive fashion.
Modern literature was reviewed for studies on SRS in the treatment of patients with brain metastases.
After assessing patient age, Karnofsky Performance Score (KPS), control of primary cancer, presence of extracranial metastases, number of brain metastases, location of brain metastases, and size of brain metastases, SRS offers suitable patients a viable, less invasive treatment option. In patients with 1 to 4 brain metastases who have a KPS ≥70, the addition of SRS to whole-brain radiation therapy (WBRT) produces increased levels of survival and local tumor control when compared with patients treated with WBRT alone. The available evidence suggests that specific patients treated with SRS alone exhibit superior levels of survival and tumor control when compared with patients treated with WBRT alone. Further evidence in the form of a randomized trial is needed to confirm this observation. Questions remain regarding survival and tumor control in patient groups treated with SRS with or without WBRT. Recently published randomized evidence reported a survival advantage in patients treated with SRS alone. These data differ from other previously published randomized evidence, as well as several prospective and retrospective studies, which reported nonsignificant survival differences. Contrasting evidence also exists pertaining to local and distant tumor control, which warrants further investigation into this matter. The available evidence suggests that in patients with 1 to 2 brain metastases, both SRS alone and SRS with WBRT offer equivalent levels of survival when compared with patients treated with surgery with WBRT. Research has been conducted that reports a survival advantage in patients with 1 to 3 brain metastases that were treated with SRS with WBRT.
SRS can be an advantageous course of treatment in specific patient groups when utilized alone, after surgery, with WBRT, or in combination with either or both of the treatment modalities. Although treatment approaches have been refined, many questions remain unanswered and further clinical evidence is needed to guide physicians in their future treatment decisions regarding treating patients in specific clinical scenarios.
立体定向放射外科（SRS）是一种放射治疗形式，它可以将高剂量的辐射聚焦于单一体积，同时最大限度地减少对相邻神经组织的损伤。SRS 在治疗脑转移瘤患者方面的疗效已得到检验，因为它能够针对大脑的任何区域，并且可以在非侵入性的方式下在同一治疗环境中照射多个肿瘤。
针对 SRS 治疗脑转移瘤患者的研究进行了现代文献综述。
评估了患者年龄、卡氏功能状态评分（KPS）、原发癌的控制情况、是否存在颅外转移、脑转移瘤的数量、脑转移瘤的位置以及脑转移瘤的大小后，SRS 为合适的患者提供了一种可行的、侵袭性较小的治疗选择。对于 KPS≥70、有 1 至 4 个脑转移瘤的患者，与单独接受全脑放疗（WBRT）相比，SRS 联合 WBRT 可提高生存率和局部肿瘤控制率。现有证据表明，与单独接受 WBRT 治疗的患者相比，单独接受 SRS 治疗的特定患者具有更高的生存率和肿瘤控制率。需要进一步的随机试验证据来证实这一观察结果。对于接受 SRS 联合或不联合 WBRT 治疗的患者群体，有关生存和肿瘤控制的问题仍然存在。最近发表的随机证据表明，单独接受 SRS 治疗的患者具有生存优势。这些数据与其他先前发表的随机证据以及几项前瞻性和回顾性研究不同，这些研究报告了无统计学意义的生存差异。关于局部和远处肿瘤控制也存在相互矛盾的证据，这需要进一步研究。现有证据表明，对于有 1 至 2 个脑转移瘤的患者，与单独接受手术联合 WBRT 治疗的患者相比，单独接受 SRS 或 SRS 联合 WBRT 治疗的患者具有相当的生存率。对于有 1 至 3 个脑转移瘤的患者，接受 SRS 联合 WBRT 治疗的患者有生存优势的研究已经开展。
SRS 可作为特定患者群体的有利治疗方法，单独使用、手术后使用、与 WBRT 联合使用，或与其中一种或两种治疗方式联合使用。尽管治疗方法已经得到了改进，但仍有许多问题尚未得到解答，需要进一步的临床证据来指导医生在特定临床情况下治疗患者的未来治疗决策。
