The Efficacy of Stereotactic Radiosurgery in the Management of Intracranial Ependymoma

OBJECTIVE: A retrospective analysis was performed to determine the outcome of patients with intracranial ependymoma treated with stereotactic radiosurgery (SRS). METHODS: Nine ependymoma patients have been treated with SRS (four with linear accelerator and five with Gamma Knife) since 1990. Two patients had WHO grade III tumors, and the remaining seven had WHO grade II tumors. Eight of nine patients received external beam radiation therapy at some point prior to radiosurgery to a total median dose of 54 Gy. The radiosurgery dose ranged from 14 to 20 Gy. RESULTS: The median follow-up was 28 months. The median age of patients at diagnosis was 35 years. Four patients developed progressive disease following radiosurgery, and two patients have died of progressive disease. The 3-year relapse-free survival was 55.6%. The 3-year overall survival was 71.1%. Patients treated with radiosurgery as a component of initial treatment (generally as a boost following external beam) had an improved relapse-free survival (100%) compared to those treated with radiosurgery to salvage an external beam local failure (20%). CONCLUSION: SRS is an effective treatment for intracranial ependymoma. Further clinical trials are warranted incorporating radiosurgery as a component of initial management in selected ependymoma patients.     

Clinical Outcomes of Intracranial Nonvestibular Schwannomas Treated with LinacBased Stereotactic Radiosurgery and Radiotherapy

Background: Intracranial nonvestibular schwannomas arising from various cranial nerves excluding CN VIII are uncommon. Recently, stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (SRT) have been widely reported as effective treatment modalities for nonvestibular schwannomas. The purpose of this study was to study the long term clinical outcome for nonvestibular schwannomas treated with both XKnife and CyberKnife (CK) radiosurgery at one institution. Materials and Methods: From 2004 to 2013, fiftytwo nonvestibular schwannoma patients were included in this study, 33 patients (63%) were treated with CK, and 19 (37%) were treated with XKnife. The majority of the tumors were jugular foramen schwannomas (38%) and trigeminal schwannomas (27%). HSRT was given for 45 patients (86%), whereas CSRT was for 6 (12%) and SRS for 1 (2%). Results: The median pretreatment volume was 9.4 cm3 (range, 0.5752 cm3). With the median follow up time of 36 months (range, 3135), the 3 and 5 year progression free survival was 94 % and 88%, respectively. Tumor size was decreased in 13 (25%), stable in 29 (56%), and increased in 10 (19%). Among the latter, 3 (30%) required additional treatment because of neurologic deterioration. No patient was found to develop any new cranial nerve deficit after SRS/SRT. Conclusions: These data confirmed that SRS/ SRT provide high tumor control rates with low complications. Large volume tumors and cystic expansion after radiation should be carefully followed up with neurological examination and MRI, because it may frequently cause neurological deterioration requiring further surgery.     

颅内生殖细胞瘤立体定向放射外科治疗失败模式和挽救性治疗的初步探讨

目的初步探讨立体定向放射初治颅内生殖细胞瘤的失败模式及挽救性治疗策略。方法回顾性分析17例接受立体定向放射治疗失败的颅内生殖细胞瘤患者的临床资料。研究治疗失败模式及挽救治疗手段。结果治疗失败时间为初治后3~24个月(中位8.5个月)。仅接受立体定向放射治疗的13例患者中,12例出现原发部位复发(6例合并颅内种植,1例合并脊髓种植),另1例出现颅内种植;接受序贯全脑或全中枢照射的4例患者,3例出现原发部位复发和颅内或脊髓种植,1例出现颅内种植。所有患者均接受挽救性治疗。全部患者均行多程含铂方案联合化疗,14例行放疗,3例未放疗,中位随访时间137.0个月,10年生存率为76.5%。结论对于明确诊断或高度怀疑为颅内生殖细胞瘤,初治不宜采用立体定向放射外科治疗作为单一治疗方法,一旦已经实施,应设法联合常规外照射放疗和/或化疗进行补救性治疗。对于复发病例,根据既往治疗情况,选用放化疗等治疗。     

Linear Accelerator Configurations for Radiosurgery

The dramatic proliferation of radiosurgery in the 1980s and 1990s has resulted in the development of a plethora of hardware systems and an exponential increase in clinical use. This article summarizes the initial, now mostly historical, developments and emphasizes that most linear accelerator radiosurgery systems are based on three early prototypical systems from Buenos Aires, Heidelberg, and Montréal. These systems have more recently been tailored to permit fractionated radiosurgery, blurring the distinction between radiosurgery and radiotherapy. The commonly used fractionated systems are described. Clinical outcome data for arteriovenous are described. Clinical outcome data for arteriovenous malformations, acoustic neuroma, and meningioma, are mostly preliminary but substantial data are available for the radiosurgical management of metastases. With the recent emphasis on cost containment, cost-effectiveness issues have become significant and at least for metastases some preliminary data suggest a potential "cost benefit" with radiosurgery. The recent publication of data from a prospective randomized trial has established the superiority of boost therapy for malignant glioma and in this article, we present preliminary evidence supporting the use of radiosurgery. Finally, some of the new and exciting developments such as the robot-mounted linear accelerator, the use of shaped fields, and tomotherapy are described.     

Radiosurgery for metastatic brain tumors

Stereotactic radiosurgery (SRS) precisely delivers high-dose radiation to a small target (usually less than 3–4 cm in diameter), in a single session with steep dose-fall, employing various radiation methods. SRS provides good tumor control for small brain metastases from various primary cancers, with minimal untoward effects on surrounding normal brain. This excellent tumor control prevents neurological death and maintains good activity of daily life. Although surgery with whole-brain radiation therapy (WBRT) remains an important option for patients with a solitary brain metastasis, SRS with or without WBRT should be considered in patients with a limited number of small tumors and a good prognosis. Many reports, as well as both retrospective and prospective reviews, have shown WBRT before or after SRS to improve local control and reduce new distant lesion emergence. However, upfront WBRT does not improve survival. There are two major delivery techniques, Gamma Knife (GK; Elekta AB, Stockholm, Sweden) SRS and linear accelerator (LINIAC)-based SRS. They are based on quite different concepts, and have different techniques and clinical applications. These differences complicate the discussion of the limitations of and indications for SRS and the necessity for prophylactic WBRT. This review discusses numerous aspects of SRS, its value as compared with other treatment modalities, the necessity for prophylactic WBRT with SRS, the limitations of and indications for SRS, and the difference between GK and LINIAC SRS, based on the literature and our experience, and proposes a new strategy for the treatment of brain metastases in view of the available clinical data and experience.