Conventionally fractionated stereotactic radiotherapy (FSRT) for acoustic neuromas

Purpose: Analysis of local tumor control and functional outcome following conventionally fractionated stereotactic radiotherapy (FSRT) for acoustic neuromas.

Patients and Methods: From 11/1989 to 9/1999 51 patients with acoustic neuromas have been treated by FSRT. Mean total dose was 57.6 ± 2.5 Gy. Forty-two patients have been followed for at least 12 months and were subject of an outcome analysis. Mean follow-up was 42 months. We analyzed local control, hearing preservation, and facial and trigeminal nerve functional preservation. We evaluated influences of tumor size, age, and association with neurofibromatosis Type 2 (NF2) on outcome and treatment related toxicity.

Results: Actuarial 2- and 5-year tumor control rates were 100% and 97.7%, respectively. Actuarial useful hearing preservation rate was 85% at 2 and 5 years. New hearing loss was diagnosed in 4 NF2 patients. Pretreatment normal facial nerve function was preserved in all cases. Two cases of new or impaired trigeminal nerve dysesthesia required medication. No other cranial nerve deficit was observed.

In Patients without NF2 tumor size or age had no influence on tumor control and cranial nerve toxicity. Diagnosis of NF2 was associated with higher risk of hearing impairment (p = 0.0002), the hearing preservation rate in this subgroup was 60%.

Conclusion: FSRT has been shown to be an effective means of local tumor control. Excellent hearing preservation rates and 5th and 7th nerve functional preservation rates were achieved. The results support the conclusion that FSRT can be recommended to patients with acoustic neuromas where special attention has to be taken to preserve useful hearing and normal cranial nerve function. For NF2 patients, FSRT may be the treatment of choice with superior functional outcome compared to treatment alternatives.     

Long-term efficacy of fractionated radiotherapy for benign meningiomas

Purpose

To assess long term efficacy of fractionated stereotactic radiotherapy (fSRT) in the treatment of benign intracranial meningiomas.

Materials and methods

Retrospective study of 222 patients with histologically confirmed (58%) and unverified presumed (42%) grade I intracranial meningioma treated with fSRT in a single institution to doses of 50–55 Gy in 30–33 fractions.

Results

At a median follow-up of 43 months (range 3–144) the 5 and 10 years local control (LC) were 93% and 86%. Patients with tumors involving the optic nerve (42 patients) and patients with cavernous sinus/parasellar region meningiomas (78 patients) had 5 and 10 years LC of 100%. The 5 and 10 years survival probabilities were 93% and 84%. On multivariate analysis gender and tumor site were independent predictors of LC.Worsening of pre-existing cranial nerve deficit occurred in 8 (3.5%) and onset of new deficit in 1 (0.5%) patient. Two patients with optic nerve sheath meningioma (1%) developed radiation retinopathy. There were no cases of radiation necrosis or second brain tumors.

Conclusion

fSRT achieves excellent medium and long term tumor control with minimal morbidity particularly in patients with benign meningiomas involving the parasellar region and the optic nerves and questions the role of other treatment modalities for tumors at these locations.     

FSRT联合替莫唑胺治疗大体积脑转移瘤的对照研究

目的 回顾比较应用分次立体定向放疗(FSRT)±替莫唑胺治疗大体积脑转移瘤患者疗效及安全性。方法 2009—2017年间共84例脑转移瘤患者(体积≥ 6 cm³)纳入分析,其中同步放化疗组(CRT组) 与单纯放疗组(RT组)各42例。放疗方案为52.0~52.5 Gy分13~15次,3.5~4.0 Gy/次。疗中复查脑MRI,如病灶体积明显缩小则行疗中缩野。疗后2~3个月评估疗效。主要研究终点为LRFS,次要研究终点为IPFS、PFS、OS、BMSS及不良反应。采用Kaplan-Meier法计算生存率并Logrank法检验和单因素预后分析。结果 CRT、RT组的中位GTV体积分别为16.9、15.7 cm³,疗中缩野率分别为75%、34%(P=0.000)。CRT、RT组LC率分别为100%、98%。中位随访时间为16.1个月(2.1~105.7个月),CRT组LRFS、IPFS、PFS、OS、BMSS均显著优于RT组(P=0.040、0.022、0.045、0.013、0.006)。1—2级消化道不良反应CRT组高于RT组(33%∶26%,P=0.006),两组均无4— 5级不良反应发生。结论 FSRT联合替莫唑胺进一步提高了大体积脑转移瘤患者的LC率及生存率且未增加严重不良反应。     

头颈肿瘤立体定向分次照射靶区定位的误差分析

背景与目的:明确靶区定位的精确度是立体定向分次照射质量保证的基本要求。本文主要分析头颈肿瘤立体定向分次照射(fractionatedstereotacticradiotherapy,FSRT)中机械等中心、CT定位、治疗摆位以及CT图像误差等可能引起的靶区定位误差。方法:使用立体定向治疗计划系统、靶点模拟器、头部定位框架检查各个治疗阶段靶区定位的误差。设置任意5个参考点,使用靶点模拟器检查CT定位误差;选取7个不同机器臂架/治疗床角度,定期用胶片检验使用的PhilipsSL-18直线加速器等中心误差大小;用验证片检查治疗摆位误差;对自制模体行CT扫描,分析CT图像伪影可能引起的图像误差。结果:CT定位误差约为(1.5±0.4)mm;在检查的不同机器臂架/治疗床角度中机械等中心最大误差为(1.0±0.6)mm;患者摆位的距离误差为(1.0±0.3)mm;整个治疗过程中靶区定位误差约为(2.1±0.8)mm。结论:立体定向分次照射中需要综合考虑各个阶段中可能对治疗靶区定位产生的影响,误差分析结果可用来确定治疗的计划靶区。     

Stereotactic radiosurgery and fractionated stereotactic radiotherapy for the treatment of acoustic schwannomas: comparative observations of 125 patients treated at one institution

Stereotactic radiosurgery (SRS) and, more recently, fractionated stereotactic radiotherapy (SRT) have been recognized as noninvasive alternatives to surgery for the treatment of acoustic schwannomas. We review our experience of acoustic tumor treatments at one institution using a gamma knife for SRS and the first commercial world installation of a dedicated linac for SRT.

Patients were treated with SRS on the gamma knife or SRT on the linac from October 1994 through August 2000. Gamma knife technique involved a fixed-frame multiple shot/high conformality single treatment, whereas linac technique involved daily conventional fraction treatments involving a relocatable frame, fewer isocenters, and high conformality established by noncoplanar arc beam shaping and differential beam weighting.

Sixty-nine patients were treated on the gamma knife, and 56 patients were treated on the linac, with 1 NF-2 patient common to both units. Three patients were lost to follow-up, and in the remaining 122 patients, mean follow-up was 119 ± 67 weeks for SRS patients and 115 ± 96 weeks for SRT patients. Tumor control rates were high (≥97%) for sporadic tumors in both groups but lower for NF-2 tumors in the SRT group. Cranial nerve morbidities were comparably low in both groups, with the exception of functional hearing preservation, which was 2.5-fold higher in patients who received conventional fraction SRT.

SRS and SRT represent comparable noninvasive treatments for acoustic schwannomas in both sporadic and NF-2 patient groups. At 1-year follow-up, a significantly higher rate of serviceable hearing preservation was achieved in SRT sporadic tumor patients and may therefore be preferable to alternatives including surgery, SRS, or possibly observation in patients with serviceable hearing.     

Hypofractionated stereotactic radiotherapy in combination with whole brain radiotherapy for brain metastases

BACKGROUND: The efficacy and toxicity of hypofractionated stereotactic radiotherapy (HSRT) in combination with whole brain radiotherapy (WBRT), for the treatment of 1-4 brain metastases, using a non invasive fixation of the skull, was investigated. METHODS: Between 04/2001 and 01/2006 30 patients with 44 brain metastases underwent irradiation. Every patient received WBRT (10 x 3 Gy); 41/44 lesions received HSRT boost with a median dose fraction of 6 Gy, the fractionation schemes were 3 x 6 Gy and 4 x 8 Gy; a median total dose of 18 Gy was delivered to the tumor isocenter. RESULTS: The median survival period was 9.15 months, the actuarial 1-year overall survival and freedom from new brain metastases were 36.6% and 87.9%, respectively; at univariate analysis Karnofsky Performance Status (KPS) was statistically significant (P = 0.05); the actuarial 1-year local control for the 41/44 lesions was 86.1%. No patient had acute or late complications. CONCLUSIONS: HSRT as a concomitant boost during WBRT is a safe and well tolerated treatment for selected patients with brain metastases.     

Outcome of fractionated stereotactic radiotherapy for 90 patients with locally persistent and recurrent nasopharyngeal carcinoma

PURPOSE: Local recurrence remains one of the major causes of failure in nasopharyngeal carcinoma (NPC). Stereotactic radiosurgery and fractionated stereotactic radiation therapy (FSRT) have recently evolved as a salvage option of NPC. This study was conducted to review the treatment outcome after FSRT for NPC. METHODS AND MATERIALS: Between September 1999 and December 2005, 90 patients with persistent (Group 1: n = 34, relapse within 6 months of RT) or recurrent (Group 2: n = 56, relapse beyond 6 months) NPC received FSRT using multiple noncoplanar arcs of 8-MV photon to the target. Median FSRT dose was 18 Gy in three fractions (Group 1) or 48 Gy in six fractions (Group 2). Median follow-up was 20.3 months. RESULTS: Complete response rate after FSRT was 66% for Group 1 and 63% for Group 2. One-, 2-, and 3-year disease-specific survival (DSS) and progression-free survival (PFS) rates for all patients were 82.6%, 74.8%, 57.5%, and 72.9%, 60.4%, 54.5%, respectively. Three-year local failure-free survival, DSS, and PFS rates were 89.4%, 80.7%, and 72.3% for Group 1, and 75.1%, 45.9%, and 42.9% for Group 2, respectively. Multivariate analysis showed that recurrent disease and large tumor volume were independent factors that predicted poorer DSS and PFS. Seventeen patients developed late complications, including 2 with fatal hemorrhage. CONCLUSIONS: Our results indicate that FSRT is effective for patients with persistent and recurrent NPC. Compared with reported results of radiosurgery, FSRT provides satisfactory tumor control and survival with a lower risk of complications and it may be a better treatment for local failures of NPC.     

脑转移瘤X线立体定向放射治疗的疗效及影响因素

背景与目的:X线立体定向放射治疗(X-ray stereotactic radiotherapy,SRT)是治疗脑转移瘤的有效方法之一,该研究意在评价脑转移瘤患者SRT的疗效以及影响预后的因素。方法:自1999年7月至2004年12月止,78例脑转移瘤患者在本中心接受SRT方式治疗。其中,49例为单发病灶,29例为多发(2～6个)病灶,总病灶数为122个。38个病灶采用SRT单次治疗,中位处方剂量为15Gy(11～24Gy)。84个病灶采用SRT分次(2～6次)治疗,中位处方剂量为24Gy(11～40Gy)。39例SRT联合全脑放疗30～40Gy。无进展生存率(progression-free survival,PFS)和总生存率(overall survival,OS)分析采用Kaplan-Meier法,单因素和多因素分析分别采用log-rank法和Cox模型。结果:中位生存时间12.9(1.7～77.4)个月。1年颅内PFS为87.4%,1和2年OS分别为53.9%和25.8%。单因素分析显示治疗前KPS(karnofsky performance state)≥70、颅外肿瘤获控制和SRT联合全脑放疗的...     

Seizure control following radiotherapy in patients with diffuse gliomas: a retrospective study

Background

Little information is available regarding the effect of conventional radiotherapy on glioma-related seizures.

Methods

In this retrospective study, we analyzed the seizure response and outcome following conventional radiotherapy in a cohort of 43 patients with glioma (33 grade II, 10 grade III) and medically intractable epilepsy.

Results

At 3 months after radiotherapy, seizure reduction was significant (≥50% reduction of frequency compared with baseline) in 31/43 patients (72%) of the whole series and in 25/33 patients (76%) with grade II gliomas, whereas at 12 months seizure reduction was significant in 26/34 (76%) and in 19/25 (76%) patients, respectively. Seizure reduction was observed more often among patients displaying an objective tumor response on MRI, but patients with no change on MRI also had a significant seizure reduction. Seizure freedom (Engel class I) was achieved at 12 months in 32% of all patients and in 38% of patients with grade II tumors. Timing of radiotherapy and duration of seizures prior to radiotherapy were significantly associated with seizure reduction.

Conclusions

This study showed that a high proportion of patients with medically intractable epilepsy from diffuse gliomas derive a significant and durable benefit from radiotherapy in terms of epilepsy control and that this positive effect is not strictly associated with tumor shrinkage as shown on MRI. Radiotherapy at tumor progression seems as effective as early radiotherapy after surgery. Prospective studies must confirm and better characterize the response to radiotherapy.     

颅脑X刀治疗脑转移瘤临床疗效分析

目的探讨颅脑X刀治疗恼转移瘤的疗效。方法98例有原发灶或转移灶病理报告的脑转移患者进行颅脑X刀治疗,边缘剂量8 Gy/次,共4次,隔日1次。并在颅脑X刀治疗前或后进行了全脑放疗,2 Gy/次,共20次。对其近期和远期疗效进行分析。结果全组病例随访12～52个月,中位随访时间30个月,随访率为94%。全组中位生存时间、1年生存率分别为10个月、41%。单发脑转移瘤与多发脑转移瘤患者中位生存时间、1年生存率分别为12个月、45%与7个月、38%,两组患者生存率差异无统计学意义(P=0.181)。临床缓解率为83%,6个月的病灶控制率为82.0%。病灶体积≤14.1 cm~3和>14.1 cm~3的控制率分别为85%和60%(P=0.029),放疗前肿瘤坏死率分别为13%和60%(P=0.000)。肿瘤中心发生坏死的病灶21个,其病灶控制率为62%,低于无坏死病灶87%的结果(P=0.013)。不同病理类型脑转移病灶的局部控制率无差异。结论颅脑X刀治疗能延长所有病理类型脑转移瘤患者的中位生存期。体积≤14.1 cm~3的脑转移病灶的局部控制率较高。     

Single-fraction vs. fractionated linac-based stereotactic radiosurgery for vestibular schwannoma: a single-institution study

PURPOSE: In this single-institution trial, we investigated whether fractionated stereotactic radiation therapy is superior to single-fraction linac-based radiosurgery with respect to treatment-related toxicity and local control in patients with vestibular schwannoma. METHODS AND MATERIALS: All 129 vestibular schwannoma patients treated between 1992 and June 2000 at our linac-based radiosurgery facility were analyzed with respect to treatment schedule. Dentate patients were prospectively selected for a fractionated schedule of 5 x 4 Gy and later on 5 x 5 Gy at the 80% isodose in 1 week with a relocatable stereotactic frame. Edentate patients were prospectively selected for a nonfractionated treatment of 1 x 10 Gy and later on 1 x 12.5 Gy at 80% isodose with an invasive stereotactic frame. Both MRI and CT scans were made in all 129 patients within 1 week before treatment. All patients were followed yearly with MRI and physical examination. RESULTS: A fractionated schedule was given to 80 patients and a single fraction to 49 patients. Mean follow-up time was 33 months (range: 12-107 months). There was no statistically significant difference between the single-fraction group and the fractionated group with respect to mean tumor diameter (2.6 vs. 2.5 cm) or mean follow-up time (both 33 months). Only mean age (63 years vs. 49 years) was statistically significantly different (p = 0.001). Outcome differences between the single-fraction treatment group and the fractionated treatment group with respect to 5-year local control probability (100% vs. 94%), 5-year facial nerve preservation probability (93% vs. 97%), and 5-year hearing preservation probability (75% vs. 61%) were not statistically significant. The difference in 5-year trigeminal nerve preservation (92% vs. 98%) reached statistical significance (p = 0.048). CONCLUSION: Linac-based single-fraction radiosurgery seems to be as good as linac-based fractionated stereotactic radiation therapy in vestibular schwannoma patients, except for a small difference in trigeminal nerve preservation rate in favor of a fractionated schedule.     

Reliability of the bony anatomy in image-guided stereotactic radiotherapy of brain metastases

PURPOSE: To evaluate whether the position of brain metastases remains stable between planning and treatment in cranial stereotactic radiotherapy (SRT). METHODS AND MATERIALS: Eighteen patients with 20 brain metastases were treated with single-fraction (17 lesions) or hypofractionated (3 lesions) image-guided SRT. Median time interval between planning and treatment was 8 days. Before treatment a cone-beam CT (CBCT) and a conventional CT after application of i.v. contrast were acquired. Setup errors using automatic bone registration (CBCT) and manual soft-tissue registration of the brain metastases (conventional CT) were compared. RESULTS: Tumor size was not significantly different between planning and treatment. The three-dimensional setup error (mean +/- SD) was 4.0 +/- 2.1 mm and 3.5 +/- 2.2 mm according to the bony anatomy and the lesion itself, respectively. A highly significant correlation between automatic bone match and soft-tissue registration was seen in all three directions (r >/= 0.88). The three-dimensional distance between the isocenter according to bone match and soft-tissue registration was 1.7 +/- 0.7 mm, maximum 2.8 mm. Treatment of intracranial pressure with steroids did not influence the position of the lesion relative to the bony anatomy. CONCLUSION: With a time interval of approximately 1 week between planning and treatment, the bony anatomy of the skull proved to be an excellent surrogate for the target position in image-guided SRT.     

Accuracy of MRI-CT registration in brain stereotactic radiotherapy: Impact of MRI acquisition setup and registration method

BackgroundIn MR-based radiotherapy (RT), MRI images are co-registered to the planning CT to leverage MR image information for RT planning. Especially in brain stereotactic RT, where typical CTV-PTV margins are 1-2 mm, high registration accuracy is critical. Several factors influence the registration accuracy, including the acquisition setup during MR simulation and the registration methods.PurposeIn this work, the impact of the MRI acquisition setup and registration method was evaluated in the context of brain RT, both geometrically and dosimetrically.Methods and MaterialsMRI of 20 brain radiotherapy patients was acquired in two MRI acquisition setups (RT and diagnostic). Three different automatic registration tools provided by three treatment planning systems were used to rigidly register both MRIs and CT in addition to the clinical registration. Segmentation-based evaluation using Hausdorff Distance (HD)/Dice Similarity Coefficient and landmark-based evaluation were used as evaluation metrics. Dose-volume-histograms were evaluated for target volumes and various organs at risks.ResultsMRI acquisition in the RT setup provided a similar head extension as compared to the planning CT. The registration method had a more significant influence than the acquisition setup (Wilcoxon signed-rank test, p<0.05). When registering using a less optimal registration method, the RT setup improved the registration accuracy compared to the diagnostic setup (Difference: ΔMHD = 0.16 mm, ΔHD_P95 = 0.64 mm, mean Euclidean distance (ΔmEuD) = 2.65 mm). Different registration methods and acquisition setups lead to the variation of the clinical DVH. Acquiring MRI in the RT setup can improve PTV and GTV coverage compared to the diagnostic setup.ConclusionsBoth MRI acquisition setup and registration method influence the MRI-CT registration accuracy in brain RT patients geometrically and dosimetrically. MR-simulation in the RT setup assures optimal registration accuracy if automatic registration is impaired, and therefore recommended for brain RT.     

Fractionated stereotactic radiotherapy in patients with primary hepatocellular carcinoma

OBJECTIVE: The purpose of our study was to evaluate the feasibility and treatment outcomes of fractionated stereotactic radiotherapy (SRT) for primary hepatocellular carcinoma (HCC). METHODS: We enrolled 20 patients who had been histologically diagnosed as HCC patients and treated by fractionated SRT. Tumor size was 2-6.5 cm (average: 3.8 cm). We prescribed 50 Gy in 5 or 10 fractions at the 85-90% isodose line of the planning target volume for 2 weeks. The follow-up period was 3-55 months (median: 23 months). RESULTS: The overall response rate was 80%, with 4 patients showing complete response (20%), 14 patients showing partial response (60%) and 4 patients showing stable disease (20%). The 1-year and 2-year survival rates were 70.0 and 43.1%, respectively (median: 20 months). The 1-year and 2-year disease-free survival rates were 65.0 and 32.5%, respectively (median: 19 months). The fractionated SRT was well tolerated, because grade 3 or grade 4 toxicity was not observed. CONCLUSION: These results suggest that fractionated SRT is a relatively safe and effective method for treating small primary HCC. Thus, fractionated SRT may be suggested as a local treatment of choice for small HCC when the patients are inoperable or when the patients refuse operation.     

Design and implementation of a system for treating paediatric patients with stereotactically-guided conformal radiotherapy

Background and purpose: Stereotactically-guided conformal radiotherapy (SCRT) allows the delivery of highly conformal dose distributions to localised brain tumours. This is of particular importance for children, whose often excellent long-term prognosis should be accompanied by low toxicity. The commercial immobilisation system in use at our hospital for adults was felt to be too heavy for children, and precluded the use of anaesthesia, which is sometimes required for paediatric patients. This paper therefore describes the design and implementation of a system for treating children with SCRT. This system needed to be well tolerated by patients, with good access for treating typical childhood malignancies.

Materials and methods: A lightweight frame was developed for immobilisation, with a shell-based alternative for patients requiring general anaesthetic. Procedures were set up to introduce the patients to the frame system in order to maximise patient co-operation and comfort. Film measurements were made to assess the impact of the frame on transmission and surface dose. The reproducibility of the systems was assessed using electronic portal images.

Results: Both frame and shell systems are in clinical use. The frame weighs 0.6 kg and is well tolerated. It has a transmission of 92–96%, and fields which pass through it deliver surface doses of 58–82% of the dose at d_max, compared to 18% when no frame is present. However, the frame is constructed to maximise the availability of unobstructed beam directions. Reproducibility measurements for the frame showed a mean random error of 1.0±0.2 mm in two dimensions (2D) and 1.4±0.7 mm in 3D. The mean systematic error in 3D was 2.2 mm, and 90% of all overall 3D errors were less than 3.4 mm. For the shell system, the mean 2D random error was 1.5±0.2 mm.

Conclusions: Two well-tolerated immobilisation devices have been developed for fractionated SCRT treatment of paediatric patients. A lightweight frame system gives a wide range of possible unobstructed beam directions, although beams that intersect the frame are not precluded, provided that output corrections are applied. A shell system allows the use of general anaesthesia. Both systems give reproducible immobilisation to complement the high-precision treatment delivery.     

Prospective study of stereotactic radiosurgery without whole brain radiotherapy in patients with four or less brain metastases: incidence of intracranial progression and salvage radiotherapy

This prospective study was conducted to evaluate the treatment outcome after stereotactic radiosurgery (SRS) alone with special attention to its influence on intracranial freedom from progression (FFP), local control, time to whole brain radiotherapy (WBRT), and survival. Forty-one patients with brain metastases who met the inclusion criteria were enrolled in this prospective cohort and treated by SRS alone between January 1998 and September 2001. The overall local control rate was 76%. The one year actuarial intracranial FFP was 33%. Ten patients (24%) had relapse at treated site. Twenty-three patients (56%) had intracranial progression with a median time of 4.25 months (1–24.6). Salvage radiotherapy was given in 21 patients (51%). Only 12 (29%) patients required WBRT with the median time to WBRT after SRS of 4.85 months. Nine patients (22%) underwent additional SRS at the median time of 5 months after the first procedure. The median survival was 10 months. At the time of follow up, 16 patients (39%) were still alive with a range of 6–31 months. This prospective study suggests that the omission of WBRT in the initial treatment of patients with SRS for four or less brain metastases may allow up to 70% of patients to avoid WBRT.