Early brain tumor metastasis reduction following Gamma Knife surgery

Radiosurgery-induced early changes in peritumoral tissue sodium concentration of brain metastases

BACKGROUND

Stereotactic radiosurgery (SRS) is an effective therapy for brain metastases. Response is assessed with serial 1H magnetic resonance imaging (MRI). Early markers for response are desirable to allow for individualized treatment adaption. Previous studies indicated that radiotherapy might have impact on tissue sodium concentration. Thus, 23Na MRI could provide early quantification of response to SRS.

PURPOSE

We investigated whether longitudinal detection of tissue sodium concentration alteration within brain metastases and their peritumoral tissue after SRS with 23Na MRI was feasible.

STUDY TYPE

Prospective.

POPULATION

Twelve patients with a total of 14 brain metastases from various primary tumors.

ASSESSMENT

23Na MRI scans were acquired from patients 2 days before, 5 days after, and 40 days after SRS. Gross tumor volume (GTV) and healthy-appearing regions were manually segmented on the MPRAGE obtained 2 days before SRS, onto which all 23Na MR images were coregistered. Radiation isodose areas within the peritumoral tissue were calculated with the radiation planning system. Tissue sodium concentration before and after SRS within GTV, peritumoral tissue, and healthy-appearing regions as well as the routine follow-up with serial MRI were evaluated.

STATISTICAL TESTS

Results were compared using Student's t-test and correlation was evaluated with Pearson's correlation coefficient.

RESULTS

We found a positive correlation between the tissue sodium concentration within the peritumoral tissue and radiation dosage. Two patients showed local progression and a differing tissue sodium concentration evolution within GTV and the peritumoral tissue compared to mean tissue sodium concentration of the other patients. No significant tissue sodium concentration changes were observed within healthy-appearing regions.

CONCLUSION

Tissue sodium concentration assessment within brain metastases and peritumoral tissue after SRS with 23Na MRI is feasible and might be able to quantify tissue response to radiation.

Real-time PACS-integrated longitudinal brain metastasis tracking tool provides comprehensive assessment of treatment response to radiosurgery

Background

Treatment of brain metastases can be tailored to individual lesions with treatments such as stereotactic radiosurgery. Accurate surveillance of lesions is a prerequisite but challenging in patients with multiple lesions and prior imaging studies, in a process that is laborious and time consuming. We aimed to longitudinally track several lesions using a PACS-integrated lesion tracking tool (LTT) to evaluate the efficiency of a PACS-integrated lesion tracking workflow, and characterize the prevalence of heterogenous response (HeR) to treatment after Gamma Knife (GK).

Methods

We selected a group of brain metastases patients treated with GK at our institution. We used a PACS-integrated LTT to track the treatment response of each lesion after first GK intervention to maximally seven diagnostic follow-up scans. We evaluated the efficiency of this tool by comparing the number of clicks necessary to complete this task with and without the tool and examined the prevalence of HeR in treatment.

Results

A cohort of eighty patients was selected and 494 lesions were measured and tracked longitudinally for a mean follow-up time of 374 days after first GK. Use of LTT significantly decreased number of necessary clicks. 81.7% of patients had HeR to treatment at the end of follow-up. The prevalence increased with increasing number of lesions.

Conclusions

Lesions in a single patient often differ in their response to treatment, highlighting the importance of individual lesion size assessments for further treatment planning. PACS-integrated lesion tracking enables efficient lesion surveillance workflow and specific and objective result reports to treating clinicians.

Gamma Knife radiosurgery as a primary treatment for central neurocytoma

OBJECTIVE

This study was performed to evaluate the role of Gamma Knife radiosurgery (GKRS) as a primary treatment for central neurocytomas (CNs).

METHODS

The authors retrospectively assessed the treatment outcomes of patients who had undergone primary treatment with GKRS for CNs in the period between December 2001 and December 2018. The diagnosis of CN was based on findings on neuroimaging studies. The electronic medical records were retrospectively reviewed for additional relevant preoperative data, and clinical follow-up data had been obtained during office evaluations of the treated patients. All radiographic data were reviewed by a dedicated neuroradiologist.

RESULTS

Fourteen patients were treated with GKRS as a primary treatment for CNs in the study period. Seven patients (50.0%) were asymptomatic at initial presentation, and 7 (50.0%) presented with headache. Ten patients (71.4%) were treated with GKRS after the diagnosis of CN based on characteristic MRI findings. Four patients (28.6%) initially underwent either stereotactic or endoscopic biopsy before GKRS. The median tumor volume was 3.9 cm3 (range 0.46–18.1 cm3). The median prescription dose delivered to the tumor margin was 15 Gy (range 5.5–18 Gy). The median maximum dose was 30 Gy (range 11–36 Gy). Two patients were treated with fractionated GKRS, one with a prescription dose of 21 Gy in 3 fractions and another with a dose of 22 Gy in 4 fractions. Control of tumor growth was achieved in all 14 patients. The median volume reduction was 26.4% (range 0%–78.3%). Transient adverse radiation effects were observed in 2 patients but resolved with improvement in symptoms. No recurrences were revealed during the follow-up period, which was a median of 25 months (range 12–89 months).

CONCLUSIONS

Primary GKRS for CNs resulted in excellent tumor control rates without recurrences. These results suggest that GKRS may be a viable treatment option for patients with small- to medium-sized or incidental CNs.

MRI characteristics in treatment for cerebral melanoma metastasis using stereotactic radiosurgery and concomitant checkpoint inhibitors or targeted therapeutics

Introduction

Combination therapy for melanoma brain metastases (MM) using stereotactic radiosurgery (SRS) and immune checkpoint-inhibition (ICI) or targeted therapy (TT) is currently of high interest. In this collective, time evolution and incidence of imaging findings indicative of pseudoprogression is sparsely researched. We therefore investigated time-course of MRI characteristics in these patients.

Methods

Data were obtained retrospectively from 27 patients (12 female, 15 male; mean 61 years, total of 169 MMs). Single lesion volumes, total MM burden and edema volumes were analyzed at baseline and follow-up MRIs in 2 months intervals after SRS up to 24 months. The occurrence of intralesional hemorrhages was recorded.

Results

17 patients (80 MM) received ICI, 8 (62 MM) TT and 2 (27 MM) ICI + TT concomitantly to SRS. MM-localization was frontal (n = 89), temporal (n = 23), parietal (n = 20), occipital (n = 10), basal ganglia/thalamus/insula (n = 10) and cerebellar (n = 10). A volumetric progression of MM 2–4 months after SRS was observed in combined treatment with ICI (p = 0.028) and ICI + TT (p = 0.043), whereas MMs treated with TT showed an early volumetric regression (p = 0.004). Edema volumes moderately correlated with total MM volumes (r = 0.57; p < 0.0001). Volumetric behavior did not differ significantly over time regarding lesions’ initial sizes or localizations. No significant differences between groups were observed regarding rates of post-SRS intralesional hemorrhages.

Conclusion

Reversible volumetric increases in terms of pseudoprogression are observed 2–4 months after SRS in patients with MM concomitantly treated with ICI and ICI + TT, rarely after TT. Edema volumes mirror total MM volumes. Medical treatment type does not significantly affect rates of intralesional hemorrhage.

Volumetric Regression in Brain Metastases After Stereotactic Radiotherapy: Time Course, Predictors, and Significance

Background

There is insufficient understanding of the natural course of volumetric regression in brain metastases after stereotactic radiotherapy (SRT) and optimal volumetric criteria for the assessment of response and progression in radiotherapy clinical trials for brain metastases are currently unknown.

Methods

Volumetric analysis via whole-tumor segmentation in contrast-enhanced 1 mm³-isotropic T1-Mprage sequences before SRT and during follow-up. A total of 3,145 MRI studies of 419 brain metastases from 189 patients were segmented. Progression was defined using a volumetric extension of the RANO-BM criteria. A subset of 205 metastases without progression/radionecrosis during their entire follow-up of at least 3 months was used to study the natural course of volumetric regression after SRT. Predictors for volumetric regression were investigated. A second subset of 179 metastases was used to investigate the prognostic significance of volumetric response at 3 months (defined as ≥20% and ≥65% volume reduction, respectively) for subsequent local control.

Results

Median relative metastasis volume post-SRT was 66.9% at 6 weeks, 38.6% at 3 months, 17.7% at 6 months, 2.7% at 12 months and 0.0% at 24 months. Radioresistant histology and FSRT vs. SRS were associated with reduced tumor regression for all time points. In multivariate linear regression, radiosensitive histology (p=0.006) was the only significant predictor for metastasis regression at 3 months. Volumetric regression ≥20% at 3 months post-SRT was the only significant prognostic factor for subsequent control in multivariate analysis (HR 0.63, p=0.023), whereas regression ≥65% was no significant predictor.

Conclusions

Volumetric regression post-SRT does not occur at a constant rate but is most pronounced in the first 6 weeks to 3 months. Despite decreasing over time, volumetric regression continues beyond 6 months post-radiotherapy and may lead to complete resolution of controlled lesions by 24 months. Radioresistant histology is associated with slower regression. We found that a cutoff of ≥20% regression for the volumetric definition of response at 3 months post-SRT was predictive for subsequent control whereas the currently proposed definition of ≥65% was not. These results have implications for standardized volumetric criteria in future radiotherapy trials for brain metastases.

MRI Detection of Changes in Tissue Sodium Concentration in Brain Metastases after Stereotactic Radiosurgery: A Feasibility Study

BACKGROUND AND PURPOSE

To date, treatment response to stereotactic radiosurgery (SRS) in brain metastases (BM) can only be determined by MRI evaluation of contrast-enhancing lesions in a long-time follow-up. Sodium MRI has been a subject of immense interest in imaging research as the measure of tissue sodium concentration (TSC) can give valuable quantitative information on cell viability. We aimed to analyze the longitudinal changes of TSC in BM measured with ²³ Na MRI before and after SRS for assessment of early local tumor effects.

METHODS

Seven patients with a total of 12 previously untreated BM underwent SRS with 22 Gy. In addition to a standard MRI protocol including dynamic susceptibility-weighted contrast-enhanced perfusion, a ²³ Na MRI was performed at three time points: (I) 2 days before, (II) 5 days, and (III) 40 days after SRS. Nine BMs were evaluated. The absolute TSC in the BM, the respective peritumoral edemas, and the normal-appearing corresponding contralateral brain area were assessed and the relative TSC were correlated to the changes in BM longest axial diameters.

RESULTS

TSC was elevated in nine BM at baseline before SRS with a mean of 73.4 ± 12.3 mM. A further increase in TSC was observed 5 days after SRS in all the nine BM with a mean of 86.9 ± 13 mM. Eight of nine BM showed a mean 60.6 ± 13.3% decrease in the longest axial diameter 40 days after SRS; at this time point, the TSC also had decreased to a mean 65.1 ± 7.9 mM. In contrast, one of the nine BM had a 13.4% increase in the largest axial diameter at time point III. The TSC of this BM showed a further TSC increase of 80.1 mM 40 days after SRS.

CONCLUSION

Changes in TSC using ²³ Na MRI shows the possible capability to detect radiobiological changes in BM after SRS.

Radiographic Trends for Infield Recurrence After Radiosurgery for Cerebral Metastases

Objective Recurrence following stereotactic radiosurgery (SRS) for the treatment of cerebral metastases is not uncommon. Recurrence can represent recurrent tumor and/or radiation necrosis. The radiographic response to Gamma Knife (GK) treatment is variable with some remaining stable, some decreasing in size, some increasing in size, while some may show a combination of all three. For tumors that demonstrate progression on MRI, the question to intervene with additional surgical or radiation therapy and the timing of such intervention remains debatable. In this study, we retrospectively reviewed surveillance MRIs of post-GK cerebral metastases to determine if radiographic trends are a predictor of infield progression. Methods A retrospective review of cerebral metastases treated with GK radiosurgery with at least two consecutive post-GK MRI scans was performed. Infield progression was defined by new enhancement increased by at least 25% in two out of three dimensions on two consecutive scans. Primary endpoints for infield recurrence were either continued observation, therapeutic intervention, or withdrawal of care.  Results A total of 579 cerebral metastases were treated with GK radiosurgery. A total of 123 metastases demonstrated radiographic progression on one follow-up MRI scan. Of those, 75% demonstrated continued progression follow-up imaging, while 25% stabilized or regressed. For post-GK metastases demonstrating progression on two consecutive MRI scans, 85% of lesions continued to progress, whereas only 15% demonstrated stabilization or regression. A total of 91% of lesions either require intervention or demonstrate continued progression with observation at this timepoint. Cumulatively 100% of metastases with radiographic progression on ≥3 consecutive MRIs went on to need further intervention. Conclusion Approximately one-fourth of infield recurrence demonstrating progression on the first surveillance MRI will stabilize or regress. Those demonstrating infield progression on two consecutive MRI scans should be considered treatment failures. Early interventions before tumor volume increases in size or patients require high-dose steroids maybe beneficial.

Outcome of three-fraction gamma knife radiosurgery for brain metastases according to fractionation scheme: preliminary results

PURPOSE

The optimal interfraction intervals for fractionated radiosurgery has yet to be established. We investigated the outcome of fractionated gamma knife radiosurgery (FGKRS) for large brain metastases (BMs) according to different interfraction intervals.

METHODS

Between September 2016 and May 2018, a total of 45 patients who underwent FGKRS for BMs were enrolled in this study. They were divided into two groups (standard fractionation over 3 consecutive days with a 24-h interfraction interval versus prolonged fractionation over 4 or 5 days with an interfraction interval of at least 48-h). BMs with ≥ 2 cm in maximum diameter or ≥ 5 cm³ in volume were included in analysis.

RESULTS

Among 52 BMs treated with 3-fraction GKRS, 25 (48.1%) were treated with standard fractionation scheme, and 27 (51.9%) with prolonged fractionation scheme. The median follow-up period was 10.5 months (range 5-25). Local tumor control rates of the standard group were 88.9% at 6 months and 77.8% at 12 months, whereas those of the prolonged group were 100% at 6 and 12 months (p = 0.023, log-rank test). In multivariate analysis, fractionation scheme (hazard ratio [HR] 0.294, 95% CI 0.099-0.873; p = 0.027) and tumor volume (HR 0.200, 95% CI 0.051-0.781; p = 0.021) were revealed as the only significant factors affecting the local tumor control after 3-fraction GKRS.

CONCLUSIONS

Our preliminary tumor control results suggest a promising role of 3-fraction GKRS with an interfraction interval of at least 48-h. This fractionation regimen could be an effective and safe treatment option in the management of large BMs.

Effect of MRI-based semiautomatic size-assessment in cerebral metastases on the RANO-BM classification

AIM

Evaluation of a semiautomatic software algorithm for magnetic resonance imaging (MRI)-based assessment of cerebral metastases in cancer patients.

MATERIAL AND METHODS

Brain metastases (n = 131) in 38 patients, assessed by contrast-enhanced MRI, were retrospectively evaluated at two timepoints (baseline, follow-up) by two experienced neuroradiologists in a blinded manner. The response assessment in neuro-oncology (RANO) criteria for brain metastases (RANO-BM) were applied by means of a software (autoRANO-BM) as well as manually (manRANO-BM) at an interval of 3 weeks.

RESULTS

The average diameter of metastases was 12.03 mm (SD ± 6.66 mm) for manRANO-BM and 13.97 mm (SD ± 7.76 mm) for autoRANO-BM. Diameter figures were higher when using semiautomatic measurements (median = 11.8 mm) as compared to the manual ones (median = 10.2 mm; p = 0.000). Correlation coefficients for intra-observer variability were 0.993 (autoRANO-BM) and 0.979 (manRANO-BM). The interobserver variability (R1/R2) was 0.936/0.965 for manRANO-BM and 0.989/0.998 for autoRANO-BM. A total of 19 lesions (15%) were classified differently when using semiautomatic measurements. In 14 cases with suspected disease progression by manRANO-BM a stable course was found according to autoRANO-BM.

CONCLUSION

Computerized measuring techniques can aid in the assessment of cerebral metastases by reducing examiner-dependent effects and may consequently result in a different classification according to RANO-BM criteria.

The value of structured radiology reports to categorize intracranial metastases following radiation therapy

PURPOSE

Radiology descriptions of intracranial metastases following radiotherapy are often imprecise. This study sought to improve such reports by creating and disseminating a structured template that encourages discrete categorization of intracranial lesions.

METHODS

Following initiation of the structured template, a retrospective review assessed patients with intracranial metastases that underwent radiotherapy, comparing 'pre-template' with 'post-template' reports. A total of 139 patients were included; 94 patients (67.6%) were imaged pre-template, 45 (32.4%) post-template. Reports were assessed for discrete versus non-specific descriptions of lesions: '(presumed) new metastases', 'treated metastases', and 'indeterminate lesions'. Non-specific language was subdivided based on the type of lesion(s) described: e.g. 'stable enhancing foci' was deemed a non-specific description of 'treated metastases'.

RESULTS

Non-specific descriptions of lesions were used in 25/94 reports (26.6%) pre-template, and eight reports (17.8%) post-template. No significant difference was found in the frequency of inappropriate/ambiguous descriptions of intracranial lesions following template initiation (P = 0.52). However, only 27/45 (60.0%) of the reports in the post-template time period used the structured report; the other reports were written as free prose. Of the reports that did use the structured template, the authors used significantly less ambiguous language structured template (P = 0.02).

CONCLUSION

When utilized, a structured report template resulted in decreased non-specific descriptions and improved discrete characterization of intracranial metastases in patients treated with radiation. However, the frequency of non-specific language usage before and after template initiation was unchanged, probably due to poor compliance with template utilization.

Detection of residual metastatic tumor in the brain following Gamma Knife radiosurgery using a single or a series of magnetic resonance imaging scans: An autopsy study

The aim of the present study was to investigate the usefulness of magnetic resonance image (MRI) for the detection of residual tumors following Gamma Knife radiosurgery (GKR) for brain metastases based on autopsy cases. The study investigated two hypotheses: i) Whether a single MRI may detect the existence of a tumor; and ii) whether a series of MRIs may detect the existence of a tumor. The study is a retrospective case series in a single institution. A total of 11 brain metastases in 6 patients were treated with GKR between 2002 and 2011. Histopathological specimens from autopsy were compared with reconstructed follow-up MRIs. The maximum diameters of the lesions on MRI series were measured, and the size changes classified. The primary sites in the patients were the kidneys (n=2), lung (n=1), breast (n=1) and colon (n=1), as well as 1 adenocarcinoma of unknown origin. The median prescribed dose for radiosurgery was 20 Gy (range, 18-20 Gy), and median time interval between GKR and autopsy was 10 months (range, 1.6-20 months). The pathological outcomes included 7 remissions and 4 failures. Enhanced areas on gadolinium-enhanced MRI contained various components: Viable tumor cells, tumor necrosis, hemorrhage, inflammation and vessels. Regarding the first hypothesis, it was impossible to distinguish pathological failure from remission with a single MRI scan due to the presence of various components. Conversely, in treatment response (remission or failure), on time-volume curves of MRI scans were in agreement with pathological findings, with the exception of progressive disease in the acute phase (0-3 months). Thus, regarding the second hypothesis, time-volume curves were useful for predicting treatment responses. In conclusion, it was difficult to predict treatment response using a single MRI, and a series of MRI scans were required to detect the existence of a tumor.

Gamma Knife radiosurgery for the management of cerebral metastases from non–small cell lung cancer

OBJECT

Non–small cell lung cancer (NSCLC) is the most frequent cancer that metastasizes to brain. Stereotactic radiosurgery (SRS) has become the management of choice for most patients with such metastatic tumors. Therefore, the authors endeavored to elucidate the survival and SRS outcomes for patients with NSCLC metastasis at their center.

METHODS

In this single-institution retrospective analysis, the authors reviewed their experience with NSCLC metastasis during a 10-year period from 2001 to 2010. Seven hundred twenty patients underwent Gamma Knife radiosurgery. A total of 1004 SRS procedures were performed, and 3143 tumors were treated. The NSCLC subtype was adenocarcinoma in 386 patients, squamous cell carcinoma in 111 patients, and large cell carcinoma in 34 patients. The median aggregate tumor volume was 4.5 cm3 (range 0.1–88 cm3).

RESULTS

The median survival time after diagnosis of brain metastasis from NSCLC was 12.6 months, and the median survival after SRS was 8.5 months. The 1-, 2-, and 5-year survival rates after SRS were 39%, 21%, and 10%, respectively. Postradiosurgery survival was decreased in patients treated with prior whole-brain radiation therapy compared with SRS alone (p = 0.003). Aggregate tumor volume was inversely related to survival after SRS (p < 0.001), and the histological subgroups demonstrated significant survival differences (p = 0.023). The overall local tumor control rate in the entire group was 92.8%. One hundred seventy-four patients (24%) underwent repeat SRS for new or resistant metastatic deposits.

CONCLUSIONS

Stereotactic radiosurgery is an effective means of providing local control for NSCLC metastases. Neurological function and survival benefit from serial patient monitoring and repeat SRS for new tumors.

[Locoregional treatments of brain metastases for patients with metastatic cutaneous melanoma: French national guidelines]

INTRODUCTION

The management of metastatic cutaneous melanoma is changing, marked by innovative therapies. However, their respective use and place in the therapeutic strategy continue to be debated by healthcare professionals.

OBJECTIVE

The French national cancer institute has led a national clinical practice guideline project since 2008. It has carried out a review of these modalities of treatment and established recommendations.

METHODS

The clinical practice guidelines development process is based on systematic literature review and critical appraisal by experts. The recommendations are thus based on the best available evidence and expert agreement. Prior to publication, the guidelines are reviewed by independent practitioners in cancer care delivery.

RESULTS

This article presents the results of bibliographic search, the conclusions of the literature and the recommendations concerning locoregional treatments of brain metastases for patients with metastatic cutaneous melanoma.

The volumetric response of brain metastases after stereotactic radiosurgery and its post-treatment implications

BACKGROUND

Changes in tumor volume are seen on magnetic resonance imaging within weeks after stereotactic radiosurgery (SRS), but it remains unclear what clinical outcomes early radiological changes portend.

OBJECTIVE

We hypothesized that rapid, early reduction in tumor volume post-SRS is associated with prolonged local control and favorable clinical outcome.

METHODS

A retrospective review of patients treated with CyberKnife SRS for brain metastases at the University of North Carolina from 2007 to 2009 was performed. Patients with at least 1 radiological follow-up, minimal initial tumor volume of 0.1 cm, no previous focal radiation, and no recent whole-brain radiation therapy were eligible for inclusion.

RESULTS

Fifty-two patients with 100 metastatic brain lesions were analyzed and had a median follow-up of 15.6 months (range, 2-33 months) and a median of 2 (range, 1-8) metastatic lesions. In treated metastases in which there was a significant tumor volume reduction by 6 or 12 weeks post-SRS, there was no local progression for the duration of the study. Furthermore, patients with metastases that did not reduce in volume by 6 or 12 weeks post-SRS were more likely to require corticosteroids (P = .01) and to experience progression of neurological symptoms (P = .003).

CONCLUSION

Significant volume reductions of brain metastases measured at either 6 or 12 weeks post-SRS were strongly associated with prolonged local control. Furthermore, early volume reduction was associated with less corticosteroid use and stable neurological symptoms.

Brain metastasis from gastrointestinal cancers: a systematic review

BACKGROUND

Brain metastases (BM) from the gastrointestinal tract (GIT) cancers are relatively rare. Despite those advances in diagnostic and treatment options, life expectancy and quality of life in these patients are still poor. In this review, we present an overview of the studies which have been previously performed as well as a comprehensive strategy for the assessment and treatment of BM from the GIT cancers.

METHOD

To obtain information on brain metastases from GIT, we performed a systematic review of Medline, EMBASE and the Cochrane Central Register of Controlled Trials (CENTRAL). The collected data included patient characteristics, primary tumor data and brain metastases data.

RESULT

In our search of the literature, we found 74 studies between 1980 and 2011, which included 2538 patients with brain metastases originated from gastrointestinal cancer. Analysis of available data showed that among 2538 patients who had brain metastases from GIT, a total of 116 patients (4.57%) had esophageal cancer, 148 patients (5.83%) had gastric cancer, 233 patients (9.18%) had liver cancer, 13 patients had pancreas cancer (0.52%) and 2028 patients (79.90%) had colorectal cancer. The total median age of the patients was 58.9 years.

CONCLUSION

Brain metastases have been considered the most common structural neurological complication of systemic cancer. Due to poor prognosis they influence the survival rate as well as the quality of life of the patients. The treatment of cerebral metastasis depends on the patients' situation and the decisions of the treating physicians. The early awareness of a probable metastasis from GI to the brain will have a great influence on treatment outcomes as well as the survival rate and the quality-of-life of the patients.

Application of diffusion-weighted magnetic resonance imaging to predict the intracranial metastatic tumor response to gamma knife radiosurgery

To evaluate the effect of stereotactic radiosurgery (SRS) on intracranial metastases with diffusion-weighted imaging/apparent diffusion coefficient maps. A total of 107 patients with 144 metastases larger than 1 cm in diameter were retrospectively reviewed. We calculated the DWI(Tumor/white matter) ratios (DWI(T/WM) ratio) between the metastases and the normal, contralateral frontal white matter at each time point. We also recorded the ADC values for metastases (ADCT values). The DWI(T/WM) ratio and ADCT values were assessed for correlation with the patients' tumor response, brain edema, and survival. A decrease in DWI(T/WM) ratios was seen in the controlled metastases, and an increase in the DWI(T/WM) ratio were seen in the metastases with poor tumor control. On the other hand, an increase in ADCT values was seen in the controlled metastases, and a decrease in ADCT values was seen in the metastases with poor control. The differences were significant (p value: 0.001 and 0.002, respectively). Sensitivity of a decrease in the DWI(T/WM) ratio to make an early prediction of tumor control was 83.9%, and specificity was 88.5%. When using the initial ADCT values of metastases to predict tumor response, sensitivity and specificity were 85.5 and 72.7%, respectively. DWI/ADC is a practical method for studying the efficacy of SRS and predicting early metastases response progression. A decrease signal on DWI and increased ADC values are indicators of good tumor control, and reflect the beneficial effect of SRS.

Imaging changes following stereotactic radiosurgery for metastatic intracranial tumors: differentiating pseudoprogression from tumor progression and its effect on clinical practice

Stereotactic radiosurgery has become standard adjuvant treatment for patients with metastatic intracranial lesions. There has been a growing appreciation for benign imaging changes following radiation that are difficult to distinguish from true tumor progression. These imaging changes, termed pseudoprogression, carry significant implications for patient management. In this review, we discuss the current understanding of pseudoprogression in metastatic brain lesions, research to differentiate pseudoprogression from true progression, and clinical implications of pseudoprogression on treatment decisions.

Large intracranial metastatic tumors treated by Gamma Knife surgery: outcomes and prognostic factors

OBJECT

The use of radiosurgery has been well accepted for treating small to medium-size metastatic brain tumors (MBTs). However, its utility in treating large MBTs remains uncertain due to potentially unfavorable effects such as progressive perifocal brain edema and neurological deterioration. In this retrospective study the authors evaluated the local tumor control rate and analyzed possible factors affecting tumor and brain edema response.

METHODS

The authors defined a large brain metastasis as one with a measurement of 3 cm or more in at least one of the 3 cardinal planes (coronal, axial, or sagittal). A consecutive series of 109 patients with 119 large intracranial metastatic lesions were treated with Gamma Knife surgery (GKS) between October 2000 and December 2012; the median tumor volume was 16.8 cm(3) (range 6.0-74.8 cm(3)). The pre-GKS Karnofsky Performance Status (KPS) score for these patients ranged from 70 to 100. The most common tumors of origin were non-small cell lung cancers (29.4% of cases in this series). Thirty-six patients (33.0%) had previously undergone a craniotomy (1-3 times) for tumor resection. Forty-three patients (39.4%) underwent whole-brain radiotherapy (WBRT) before GKS. Patients were treated with GKS and followed clinically and radiographically at 2- to 3-month intervals thereafter.

RESULTS

The median duration of imaging follow-up after GKS for patients with large MBTs in this series was 6.3 months. In the first follow-up MRI studies (performed within 3 months after GKS), 77 lesions (64.7%) had regressed, 24 (20.2%) were stable, and 18 (15.1%) were found to have grown. Peritumoral brain edema as defined on T2-weighted MRI sequences had decreased in 79 lesions (66.4%), was stable in 21 (17.6%), but had progressed in 19 (16.0%). In the group of patients who survived longer than 6 months (76 patients with 77 MBTs), 88.3% of the MBTs (68 of 77 lesions) had regressed or remained stable at the most recent imaging follow-up, and 89.6% (69 of 77 lesions) showed regression of perifocal brain edema volume or stable condition. The median duration of survival after GKS was 8.3 months for patients with large MBTs. Patients with small cell lung cancer and no previous WBRT had a significantly higher tumor control rate as well as better brain edema relief. Patients with a single metastasis, better KPS scores, and no previous radiosurgery or WBRT were more likely to decrease corticosteroid use after GKS. On the other hand, higher pre-GKS KPS score was the only factor that showed a statistically significant association with longer survival.

CONCLUSIONS

Treating large MBTs using either microsurgery or radiosurgery is a challenge for neurosurgeons. In selected patients with large brain metastases, radiosurgery offered a reasonable local tumor control rate and favorable functional preservation. Exacerbation of underlying edema was rare in this case series. Far more commonly, edema and steroid use were lessened after radiosurgery. Radiosurgery appears to be a reasonable option for some patients with large MBTs.

Preclinical evaluation of oncolytic δγ(1)34.5 herpes simplex virus expressing interleukin-12 for therapy of breast cancer brain metastases

The metastasis of breast cancer to the brain and central nervous system (CNS) is a problem of increasing importance. As improving treatments continue to extend patient survival, the incidence of CNS metastases from breast cancer is on the rise. New treatments are needed, as current treatments are limited by deleterious side effects and are generally palliative. We have previously described an oncolytic herpes simplex virus (HSV), designated M002, which lacks both copies of the γ₁34.5 neurovirulence gene and carries a murine interleukin 12 (IL-12) expression cassette, and have validated its antitumor efficacy in a variety of preclinical models of primary brain tumors. However, M002 has not been yet evaluated for use against metastatic brain tumors. Here, we demonstrate the following: both human breast cancer and murine mammary carcinoma cells support viral replication and IL-12 expression from M002; M002 replicates in and destroys breast cancer cells from a variety of histological subtypes, including “triple-negative” and HER2 overexpressing; M002 improves survival in an immunocompetent model more effectively than does a non-cytokine control virus. Thus, we conclude from this proof-of-principle study that a γ₁34.5-deleted IL-12 expressing oncolytic HSV may be a potential new therapy for breast cancer brain metastases.

Analysis of the layering pattern of the apparent diffusion coefficient (ADC) for differentiation of radiation necrosis from tumour progression

OBJECTIVES

To evaluate the added value of diffusion-weighted imaging (DWI) to perfusion-weighted imaging (PWI) for differentiating tumour progression from radiation necrosis.

METHODS

Sixteen consecutive patients who underwent removal of a metastatic brain tumour that increased in size after stereotactic radiosurgery were retrospectively reviewed. The layering of the ADC was categorised into three patterns. ADC values were measured on each layer, and the maximum rCBV was measured. rCBV and the layering pattern of the ADC of radiation necrosis and tumour progression were compared.

RESULTS

Nine cases of radiation necrosis and seven cases of tumour progression were pathologically confirmed. Radiation necrosis (88.9 % vs. 14.3 %) showed a three-layer pattern of ADC with a middle layer of minimum ADC more frequently. If rCBV larger than 2.6 was used to differentiate radiation necrosis and tumour progression, the sensitivity was 100 % but specificity was 56 %. If the lesions with the three-layer pattern of ADC with moderately increased rCBV (2.6-4.1) were excluded from tumour progression, the sensitivity and specificity increased to 100 %.

CONCLUSIONS

The three-layer pattern of ADC shows high specificity in diagnosing radiation necrosis; therefore, combined analysis of the ADC pattern with rCBV may have added value in the correct differentiation of tumour progression from radiation necrosis.

A comprehensive review of MR imaging changes following radiosurgery to 500 brain metastases

BACKGROUND AND PURPOSE

Stereotactic radiosurgery is known to control 85%-95% of intracranial metastatic lesions during a median survival of 6-8 months. However, with the advent of newer systemic cancer therapies, survival is improving; this change mandates a longitudinal quantitative analysis of the radiographic response of brain metastases to radiosurgery.

MATERIALS AND METHODS

MR imaging of 516 metastases in 120 patients treated with GK-SRS from June 2006 to December 2009 was retrospectively reviewed. Lesion volume at initial treatment and each follow-up was calculated by using the following formula: length × width × height / 2. Volume changes were correlated with patient demographics, histopathology, and radiation treatment variables.

RESULTS

Thirty-two percent of lesions increased in volume following radiosurgery. Clinically, this translated into 54% of patients having ≥1 of their lesions increase in size. This increase begins at 6 weeks and can last beyond 15 months' post-SRS. Male sex (P = .002), mean voxel dose <37 Gy (P = .009), and initial treatment volume >500 mm(3) (P < .001) are associated with posttreatment increases in tumor size. Median survival following radiosurgery was 9.5 months for patients with all lesions exhibiting stable/decreased volumes, >18.4 months for patients with all lesions exhibiting increased volumes, and 16.4 months for patients with mixed lesional responses.

CONCLUSIONS

Most metastatic lesions are stable or smaller in size during the first 36 months post-SRS. However, a transient increase in volume is seen in approximately one-third of lesions. Sex, treatment dose, initial lesion size, and histopathology all correlate with variations in lesion volume post-SRS. The longer the patient survives, the more likely an increase in lesion size will be seen on follow-up imaging.

Radiosurgery for large brain metastases

PURPOSE

To determine the efficacy and safety of radiosurgery in patients with large brain metastases treated with radiosurgery.

PATIENTS AND METHODS

Eighty patients with large brain metastases (>14 cm(3)) were treated with radiosurgery between 1998 and 2009. The mean age was 59 ± 11 years, and 49 (61.3%) were men. Neurologic symptoms were identified in 77 patients (96.3%), and 30 (37.5%) exhibited a dependent functional status. The primary disease was under control in 36 patients (45.0%), and 44 (55.0%) had a single lesion. The mean tumor volume was 22.4 ± 8.8 cm(3), and the mean marginal dose prescribed was 13.8 ± 2.2 Gy.

RESULTS

The median survival time from radiosurgery was 7.9 months (95% confidence interval [CI], 5.343-10.46), and the 1-year survival rate was 39.2%. Functional improvement within 1-4 months or the maintenance of the initial independent status was observed in 48 (60.0%) and 20 (25.0%) patients after radiosurgery, respectively. Control of the primary disease, a marginal dose of ≥11 Gy, and a tumor volume ≥26 cm(3) were significantly associated with overall survival (hazard ratio, 0.479; p = .018; 95% CI, 0.261-0.880; hazard ratio, 0.350; p = .004; 95% CI, 0.171-0.718; hazard ratio, 2.307; p = .006; 95% CI, 1.274-4.180, respectively). Unacceptable radiation-related toxicities (Radiation Toxicity Oncology Group central nervous system toxicity Grade 3, 4, and 5 in 7, 6, and 2 patients, respectively) developed in 15 patients (18.8%).

CONCLUSION

Radiosurgery seems to have a comparable efficacy with surgery for large brain metastases. However, the rate of radiation-related toxicities after radiosurgery should be considered when deciding on a treatment modality.

Early significant tumor volume reduction after radiosurgery in brain metastases from renal cell carcinoma results in long-term survival

PURPOSE

To retrospectively evaluate survival of patients with brain metastasis from renal cell carcinoma (RCC) after radiosurgery.

PATIENTS AND METHODS

Between 1998 and 2010, 46 patients were treated with radiosurgery, and the total number of lesions was 99. The mean age was 58.9 years (range, 33-78 years). Twenty-six patients (56.5%) had a single brain metastasis. The mean tumor volume was 3.0 cm(3) (range, 0.01-35.1 cm(3)), and the mean marginal dose prescribed was 20.8 Gy (range, 12-25 Gy) at the 50% isodose line. A patient was classified into the good-response group when the sum of the volume of the brain metastases decreased to less than 75% of the original volume at a 1-month follow-up evaluation using MRI.

RESULTS

As of December 28, 2010, 39 patients (84.8%) had died, and 7 (15.2%) survived. The overall median survival time was 10.0 ± 0.4 months (95% confidence interval, 9.1-10.8). After treatment, local tumor control was achieved in 72 (84.7%) of the 85 tumors assessed using MRI after radiosurgery. The good-response group survived significantly longer than the poor-response group (median survival times of 18.0 and 9.0 months, respectively; p = 0.025). In a multivariate analysis, classification in the good-response group was the only independent prognostic factor for longer survival (p = 0.037; hazard ratio = 0.447; 95% confidence interval, 0.209-0.953).

CONCLUSIONS

Radiosurgery seems to be an effective treatment modality for patients with brain metastases from RCC. The early significant tumor volume reduction observed after radiosurgery seems to result in long-term survival in RCC patients with brain metastases.