Adler John R, Gibbs Iris C, Puataweepong Putipun, Chang Steven D
Department of Neurosurgery, Stanford University Medical School, Stanford, California, USA.
Neurosurgery. 2006 Aug;59(2):244-54; discussion 244-54. doi: 10.1227/01.NEU.0000223512.09115.3E.
The restricted radiation tolerance of the anterior visual pathways represents a unique challenge for ablating adjacent lesions with single-session radiosurgery. Although preliminary studies have recently demonstrated that multisession radiosurgery for selected perioptic tumors is both safe and effective, the number of patients in these clinical series was modest and the length of follow-up limited. The current retrospective study is intended to help address these shortcomings.
Forty-nine consecutive patients with meningioma (n = 27), pituitary adenoma (n = 19), craniopharyngioma (n = 2), or mixed germ cell tumor (n = 1) situated within 2 mm of a "short segment" of the optic apparatus underwent multisession image-guided radiosurgery at Stanford University Medical Center. Thirty-nine of these patients had previous subtotal surgical resection, and six had previously been treated with conventional fractionated radiotherapy (6). CyberKnife radiosurgery was delivered in two to five sessions to an average tumor volume of 7.7 cm3 and a cumulative average marginal dose of 20.3 Gy. Formal visual testing and clinical examinations were performed before treatment and at follow-up intervals beginning at 6 months.
After a mean visual field follow-up of 49 months (range, 6-96 mo), vision was unchanged postradiosurgery in 38 patients, improved in eight (16%), and worse in three (6%). In each instance, visual deterioration was accompanied by tumor progression that ultimately resulted in patient death. However, one of these patients, who had a multiply recurrent adrenocorticotropic hormone-secreting pituitary adenoma, initially experienced early visual loss without significant tumor progression after both a previous course of radiotherapy and three separate sessions of radiosurgery. After a mean magnetic resonance imaging follow-up period of 46 months, tumor volume was stable or smaller in all other cases. Two patients died of unrelated nonbrain causes.
Multisession radiosurgery resulted in high rates of tumor control and preservation of visual function in this group of perioptic tumors. Ninety-four percent of patients retained or improved preradiosurgical vision. This intermediate-term experience reinforces the findings from earlier studies that suggested that multisession radiosurgery can be a safe and effective alternative to either surgery or fractionated radiotherapy for selected lesions immediately adjacent to short segments of the optic apparatus.
视觉前通路有限的放射耐受性给单疗程放射外科手术切除相邻病变带来了独特挑战。尽管近期的初步研究表明，对选定的视周肿瘤进行多疗程放射外科手术既安全又有效，但这些临床系列中的患者数量不多，随访时间也有限。当前的这项回顾性研究旨在弥补这些不足。
49例连续患者，包括27例脑膜瘤、19例垂体腺瘤、2例颅咽管瘤或1例混合性生殖细胞瘤，肿瘤位于视器“短节段”2毫米范围内，在斯坦福大学医学中心接受了多疗程图像引导放射外科手术。其中39例患者先前接受过次全手术切除，6例曾接受过传统分割放疗（6）。使用射波刀进行放射外科手术，分2至5个疗程，平均肿瘤体积为7.7立方厘米，累积平均边缘剂量为20.3 Gy。在治疗前以及从6个月开始的随访间隔期进行正式的视力测试和临床检查。
平均视野随访49个月（范围6 - 96个月）后，38例患者放射外科手术后视力无变化，8例（16%）视力改善，3例（6%）视力恶化。在每种情况下，视力恶化都伴有肿瘤进展，最终导致患者死亡。然而，其中1例患有多次复发的促肾上腺皮质激素分泌型垂体腺瘤的患者，在先前的放疗疗程和3次单独的放射外科手术后，最初出现早期视力丧失，但无明显肿瘤进展。平均磁共振成像随访46个月后，所有其他病例的肿瘤体积稳定或缩小。2例患者死于与脑部无关的原因。
多疗程放射外科手术在这组视周肿瘤中实现了高肿瘤控制率和视功能保留。94%的患者保留或改善了放射外科手术前的视力。这一中期经验强化了早期研究的结果，表明对于紧邻视器短节段的选定病变，多疗程放射外科手术可以是手术或分割放疗的一种安全有效的替代方法。
