Adjuvant Whole Brain Radiotherapy: Strong Emotions Decide But Rational Studies Are Needed

Pre-operative vs. post-operative stereotactic radiosurgery for operative metastatic brain tumors: study protocol for a phase III clinical trial

BACKGROUND AND OBJECTIVES

Almost one third of cancer patients in the United States will develop brain metastases on an annual basis. Surgical resection is indicated in the setting of brain metastases for reasons, such as maximizing local control in select patients, decompression of mass effect, and/or tissue diagnosis. The current standard of care following resection of a brain metastasis has shifted from whole brain radiation therapy to post-operative stereotactic radiosurgery (SRS). However, there is a significant rate of local recurrence within one year of postoperative SRS. Emerging retrospective and prospective data suggest pre-operative SRS is a safe and potentially effective treatment paradigm for surgical brain metastases. This trial intends to determine, for patients with an indication for resection of a brain metastasis, whether there is an increase in the time to a composite endpoint of adverse outcomes; including the first occurrence of either: local recurrence, leptomeningeal disease, or symptomatic radiation brain necrosis - in patients who receive pre-operative SRS as compared to patients who receive post-operative SRS.

METHODS

This randomized phase III clinical trial compares pre-operative with post-operative SRS for brain metastases. A dynamic random allocation procedure will allocate an equal number of patients to each arm: pre-operative SRS followed by surgery or surgery followed by post-operative SRS.

EXPECTED OUTCOMES

If pre-operative SRS improves outcomes relative to post-operative SRS, this will establish pre-operative SRS as superior. If post-operative SRS proves superior to pre-operative SRS, it will remain a standard of care and halt the increasing utilization of pre-operative SRS. If there is no difference in pre- versus post-operative SRS, then pre-operative SRS may still be preferred, given patient convenience and the potential for a condensed timeline.

DISCUSSION

Emerging retrospective and prospective data have demonstrated some benefits of pre-op SRS vs. post-op SRS. This study will show whether there is an increase in the time to the composite endpoint. Additionally, the study will compare overall survival; patient-reported outcomes; morbidity; completion of planned therapies; time to systemic therapy; time to regional progression; time to CNS progression; time to subsequent treatment; rate of radiation necrosis; rate of local recurrence; and rate of leptomeningeal disease.

TRIAL REGISTRATION NUMBER

NCT03750227 (Registration date: 21/11/2018).

Advances in Radiotherapy for Brain Metastases

Radiotherapy remains a cornerstone treatment of brain metastases. With new treatment advances, patients with brain metastases are living longer, and finding solutions for mitigating treatment-related neurotoxicity and improving quality of life is important. Historically, whole-brain radiation therapy (WBRT) was widely used but treatment options such as hippocampal sparing WBRT and stereotactic radiosurgery (SRS) have emerged as promising alternatives. Herein, we discuss the recent advances in radiotherapy for brain metastases including the sparing of critical structures that may improve long-term neurocognitive outcomes (eg, hippocampus, fornix) that may improve long-term neurocognitive outcome, evidence supporting preoperative and fractionated-SRS, and treatment strategies for managing radiation necrosis.

Cerebral metastases

Brain metastases are common and deadly. Over the last 25 years GKNS has been established as an invaluable treatment. It may be used as a primary treatment or after either surgery or WBRT. Patients are assessed using one of a number of available scales. GKNS may be repeated for new metastases and for unresponsive tumors. Prescription doses are usually between 18 and 20Gy. The use of advanced MR techniques to highlight sensitive structures like the hippocampi have extended the efficacy of the treatment. More recently GKNS has been used with different target therapies with improved results. More recently frameless treatments have become more popular in this group of very sick patients. GKNS controls tumors in between 80% and over 95% of cases and may even be used for brainstem tumors.

Analysis of the drivers of cost of management when patients with brain metastases are treated with upfront radiosurgery

OBJECTIVES

We aimed to assess the driving factors for increased cost of brain metastasis management when using upfront stereotactic radiosurgery (SRS).

PATIENT AND METHODS

737 patients treated with upfront SRS without whole brain radiotherapy (WBRT). Patients were evaluated for use of craniotomy, length of hospital stay, need for rehabilitation or facility placement, and use of salvage SRS or salvage WBRT. Costs of care of these interventions were estimated based on 2013 Medicare reimbursements. Multiple linear regression was performed to determine factors that predicted for higher cost of treatment per month of life, as well as highest cumulative cost of care for brain metastasis.

RESULTS

Mean cost of brain metastasis management per patient was $42,658, and $4673 per month of life. Upfront SRS represented the greatest contributor of total cost of brain metastasis management over a lifetime (49%), followed by use of any salvage SRS (21%), use of initial surgery (14%), use of salvage surgery (10%), hospitalization (3%) and cost of salvage WBRT (3%). Multiple linear regression identified brain metastasis velocity (BMV) (p < 0.001), use of cavity-directed SRS (<0.001), and CNS symptoms at time of presentation (p = 0.005) as factors that increased costs of care per month of survival. Use of salvage WBRT decreased per month cost of care in patients requiring salvage (p < 0.001).

CONCLUSION

The cost of upfront SRS is the greatest contributor to cost of brain metastasis management when using upfront SRS. Higher BMV, progressive systemic disease and presence of symptoms are associated with increased cost of care.

The Future Is Now-Prospective Study of Radiosurgery for More Than 4 Brain Metastases to Start in 2018!

Stereotactic radiosurgery (SRS) has replaced whole brain radiotherapy (WBRT) as standard therapy for most patients with four or fewer brain metastases due to improved cognitive outcomes and more favorable health related quality of life (QoL). Whether SRS or WBRT is the optimal radiation modality for patients with five to fifteen brain metastases remains an open question. Efforts are underway to develop prospective evidence to answer this question. One of the planned trials is a Canadian Cancer Trials Group (CCTG)-lead North American intergroup trial. In general cancer treatments must have two basic aims: prolonging and improving QoL. In this vein, the selection of overall survival and QoL metrics as outcomes appear obvious. Potential secondary outcomes are numerous: patient/disease related, treatment related, economic, translational, imaging, and dosimetric. In designing a trial, one must also ponder what is standard WBRT—specifically, whether it should be associated with memantine. With the rapid accrual of an intergroup trial of hippocampal-sparing WBRT, we may find that the standard WBRT regimen changes in the course of planned trials. As up-front radiosurgery is increasingly used for more than 4 brain metastases without high level evidence, we have a window of opportunity to develop high quality evidence which will help guide our future clinical and policy decisions.

Sociodemographic predictors of patients with brain metastases treated with stereotactic radiosurgery

Background

Patient sociodemographic factors such income, race, health insurance coverage, and rural residence impact a variety of outcomes in patients with cancer. The role of brain metastasis at presentation and its subsequent outcomes have not been well characterized in this patient population.

Results

Multivariate analysis revealed that median income lower than $50,000 was associated with higher presenting symptom grade for brain metastasis (mean RTOG grade 1.2 vs 1.0, SE = 0.1, p = 0.04) and higher chronic symptom grade (mean RTOG grade 1.3 vs 0.9, SE = 0.1, p = 0.002). Higher area-level median income was associated with a lower symptom grade at diagnosis of brain metastasis (p = 0.0008) and likelihood of hospitalization (p = 0.004). Other sociodemographic factors were not significantly associated with survival, neurologic death, or patterns of failure after stereotactic radiosurgery for brain metastases.

Conclusions

Lower median income was associated with a greater symptom burden at the time of diagnosis and need for hospitalization for patients with brain metastases, suggesting a delayed time to presentation. These differences in symptom burden persisted during treatment.

Methods

Between January 2000 and December 2013, we identified 737 patients treated with stereotactic radiosurgery for brain metastases. They were characterized by 4 sociodemographic factors: median income, race, rural-urban residence, and health insurance status. Clinical outcomes included stage at diagnosis, symptom grade at presentation, likelihood of hospitalization from brain metastasis, overall survival, local failure, distant brain failure, and neurologic death. Multivariate cox proportional hazards model for each outcome was performed controlling for age, sex, number of brain metastases, and dose to brain metastases.

Prediction of new brain metastases after radiosurgery: validation and analysis of performance of a multi-institutional nomogram

Stereotactic radiosurgery (SRS) without whole brain radiotherapy (WBRT) for brain metastases can avoid WBRT toxicities, but with risk of subsequent distant brain failure (DBF). Sole use of number of metastases to triage patients may be an unrefined method. Data on 1354 patients treated with SRS monotherapy from 2000 to 2013 for new brain metastases was collected across eight academic centers. The cohort was divided into training and validation datasets and a prognostic model was developed for time to DBF. We then evaluated the discrimination and calibration of the model within the validation dataset, and confirmed its performance with an independent contemporary cohort. Number of metastases (≥8, HR 3.53 p = 0.0001), minimum margin dose (HR 1.07 p = 0.0033), and melanoma histology (HR 1.45, p = 0.0187) were associated with DBF. A prognostic index derived from the training dataset exhibited ability to discriminate patients' DBF risk within the validation dataset (c-index = 0.631) and Heller's explained relative risk (HERR) = 0.173 (SE = 0.048). Absolute number of metastases was evaluated for its ability to predict DBF in the derivation and validation datasets, and was inferior to the nomogram. A nomogram high-risk threshold yielding a 2.1-fold increased need for early WBRT was identified. Nomogram values also correlated to number of brain metastases at time of failure (r = 0.38, p < 0.0001). We present a multi-institutionally validated prognostic model and nomogram to predict risk of DBF and guide risk-stratification of patients who are appropriate candidates for radiosurgery versus upfront WBRT.

Surgery or radiosurgery plus whole brain radiotherapy versus surgery or radiosurgery alone for brain metastases

BACKGROUND

The benefits of adding upfront whole-brain radiotherapy (WBRT) to surgery or stereotactic radiosurgery (SRS) when compared to surgery or SRS alone for treatment of brain metastases are unclear.

OBJECTIVES

To compare the efficacy and safety of surgery or SRS plus WBRT with that of surgery or SRS alone for treatment of brain metastases in patients with systemic cancer.

SEARCH METHODS

We searched MEDLINE, EMBASE and The Cochrane Central Register of Controlled Trials (CENTRAL) up to May 2013 and annual meeting proceedings of ASCO and ASTRO up to September 2012 for relevant studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing surgery or SRS plus WBRT with surgery or SRS alone for treatment of brain metastases.

DATA COLLECTION AND ANALYSIS

Two review authors undertook the quality assessment and data extraction. The primary outcome was overall survival (OS). Secondary outcomes include progression free survival (PFS), local and distant intracranial disease progression, neurocognitive function (NF), health related quality of life (HRQL) and neurological adverse events. Hazard ratios (HR), risk ratio (RR), confidence intervals (CI), P-values (P) were estimated with random effects models using Revman 5.1 MAIN RESULTS: We identified five RCTs including 663 patients with one to four brain metastases. The risk of bias associated with lack of blinding was high and impacted to a greater or lesser extent on the quality of evidence for all of the outcomes. Adding upfront WBRT decreased the relative risk of any intracranial disease progression at one year by 53% (RR 0.47, 95% CI 0.34 to 0.66, P value < 0.0001, I(2) =34%, Chi(2) P value = 0.21, low quality evidence) but there was no clear evidence of a difference in  OS (HR 1.11, 95% CI 0.83 to 1.48, P value = 0.47, I(2) = 52%, Chi(2) P value = 0.08, low quality evidence) and PFS (HR 0.76, 95% CI 0.53 to 1.10, P value = 0.14, I(2) = 16%, Chi(2) P value = 0.28, low quality evidence). Subgroup analyses showed that the effects on overall survival were similar regardless of types of focal therapy used, number of brain metastases, dose and sequence of WBRT. The evaluation of the impact of upfront WBRT on NF, HRQL and neurological adverse events was limited by the unclear and high risk of reporting, performance and detection bias, and inconsistency in the instruments and methods used to measure and report results across studies.

AUTHORS' CONCLUSIONS

There is low quality evidence that adding upfront WBRT to surgery or SRS decreases any intracranial disease progression at one year. There was no clear evidence of an effect on overall and progression free survival. The impact of upfront WBRT on neurocognitive function, health related quality of life and neurological adverse events was undetermined due to the high risk of performance and detection bias, and inconsistency in the instruments and methods used to measure and report results across studies.

Adjuvant whole brain radiation following resection of brain metastases

Brain metastasis is a common complication of systemic cancer and significant cause of suffering in oncology patients. Despite a plethora of available treatment modalities, the prognosis is poor with a median survival time of approximately one year. For patients with controlled systemic disease, good performance status, and a limited number of metastases, treatment typically entails surgical resection or radiosurgery, followed by whole brain radiotherapy (WBRT) to control microscopic disease. WBRT is known to control the progression of cancer in the brain, but it can also have toxic effects, particularly with regard to neurocognition. There is no consensus as to whether the benefit of WBRT outweighs the potential harm. We review the evidence related to the question of whether patients undergoing surgical resection of brain metastases should receive adjuvant WBRT.

Implications for preserving neural stem cells in whole brain radiotherapy and prophylactic cranial irradiation: a review of 2270 metastases in 488 patients

This study delineated the incidence of metastatic involvement of neural stem cell (NSC) regions and further aimed to explore the feasibility of selectively sparing the NSC compartments during whole brain radiotherapy (WBRT) and prophylactic cranial irradiation (PCI). A total of 2270 intracranial metastases in 488 patients were identified. Lesions were classified according to locations, including lesions in the NSC compartments (subventricular zone, SVZ, or hippocampus) and those in the rest of the brain/brainstem. The incidence of involvement of NSC regions was compared between oligometastatic patients (those with 1-4 lesions) and non-oligometastatic patients (those with 5 or more lesions) using a chi-square test. The volume of the NSC regions accounted for 2.23% of the whole brain, and the overall rate of metastatic lesions in NSC regions was 1.1% in 2270 metastases (25/2270), and 4.7% in 488 patients (23/488). Of the NSC region metastases, 7 (0.3%) involved the hippocampus and 18 (0.8%) occurred in the SVZ. Among the 7 hippocampal metastases identified in this study, 1/7 (14.3%) were found in oligometastatic patients, while 6/7 (85.7%) metastases were in non-oligometastatic patients. For metastases in the SVZ, all lesions occurred in non-oligometastatic patients with none in oligometastatic patients. Metastatic involvement of the NSC compartments was significantly lower in oligometastatic patients (0.15%, 1/670) than in non-oligometastatic patients (1.5%, 24/1600) (P < 0.001). Our retrospective review of 2270 metastases in 488 patients is that the volume of the compartments of NSC regions was 2.23% relative to the whole brain, but the incidence of involvement of the NSC compartments was 1.1%, and the vast majority of NSC lesions were found in non-oligometastatic patients. We believe our data supports selective reduction of doses for these aforementioned structures, when treating oligometastatic patients with WBRT and locally advanced-stage small-cell lung cancer patients with PCI.

Radiation therapy in the management of patients with limited brain metastases

Brain metastases are the most common form of intracranial tumor in adults and an increasingly important cause of morbidity and mortality. Rising incidence is attributed to advanced radiographic imaging and prolonged survival due to improvements in cancer therapy (including systemic therapies) that are not as effective in treating intracranial disease. Standard treatment options for brain metastases include resection, whole-brain radiation therapy (WBRT), stereotactic radiosurgery, or a combination of these modalities. Most patients with brain metastases receive some form of radiation therapy during the course of their illness, and for the majority of them, the prognosis is poor and WBRT remains the standard. However, within this very diverse patient population, subgroups exist in which prolonged survival is possible. In recent years, several randomized controlled trials have clearly demonstrated the efficacy of stereotactic radiosurgery in well-selected patients. This, along with an increased recognition of the late neurocognitive effects of WBRT, has led many to question the role of upfront WBRT in patients with limited intracranial metastases. In this review, we summarize the evolving role of radiotherapy in the management of brain metastases and then discuss the issues related to neurotoxicity from radiation and future areas of investigation.

Distant metastases from head and neck squamous cell carcinoma. Part III. Treatment

Distant metastases from head and neck squamous cell carcinoma (HNSCC), though rare at initial presentation, remain an important manifestation of cancer recurrence and mortality. Although generally considered incurable with a dismal prognosis despite palliative therapy, highly selected patients with distant metastases may have a long term survival benefit from aggressive surgery or radiotherapy. Advances in systemic treatments also may improve patient survival. This article reviews the current state of management of HNSCC patients with distant metastases.

Current standards in the management of cerebral metastases

The last 30 years have seen major changes in attitude toward patients with cerebral metastases. This paper aims to outline the major landmarks in this transition and the therapeutic strategies currently used. The controversies surrounding control of brain disease are discussed, and two emerging management trends are reviewed: tumor bed radiosurgery and salvage radiation.

Rac1-regulated endothelial radiation response stimulates extravasation and metastasis that can be blocked by HMG-CoA reductase inhibitors

Radiotherapy (RT) plays a key role in cancer treatment. Although the benefit of ionizing radiation (IR) is well established, some findings raise the possibility that irradiation of the primary tumor not only triggers a killing response but also increases the metastatic potential of surviving tumor cells. Here we addressed the question of whether irradiation of normal cells outside of the primary tumor augments metastasis by stimulating the extravasation of circulating tumor cells. We show that IR exposure of human endothelial cells (EC), tumor cells (TC) or both increases TC-EC adhesion in vitro. IR-stimulated TC-EC adhesion was blocked by the HMG-CoA reductase inhibitor lovastatin. Glycyrrhizic acid from liquorice root, which acts as a Sialyl-Lewis X mimetic drug, and the Rac1 inhibitor NSC23766 also reduced TC-EC adhesion. To examine the in vivo relevance of these findings, tumorigenic cells were injected into the tail vein of immunodeficient mice followed by total body irradiation (TBI). The data obtained show that TBI dramatically enhances tumor cell extravasation and lung metastasis. This pro-metastatic radiation effect was blocked by pre-treating mice with lovastatin, glycyrrhizic acid or NSC23766. TBI of mice prior to tumor cell transplantation also stimulated metastasis, which was again blocked by lovastatin. The data point to a pro-metastatic trans-effect of RT, which likely rests on the endothelial radiation response promoting the extravasation of circulating tumor cells. Administration of the widely used lipid-lowering drug lovastatin prior to irradiation counteracts this process, likely by suppressing Rac1-regulated E-selectin expression following irradiation. The data support the concern that radiation exposure might increase the extravasation of circulating tumor cells and recommend co-administration of lipid-lowering drugs to avoid this adverse effect of ionizing radiation.

Management of brain metastases

OPINION STATEMENT

As systemic cancer therapies have improved, the natural history and importance of treating brain metastases continues to evolve. Historically, most patients with brain metastases have been managed with whole brain radiation therapy (WBRT) with surgical resection or radiosurgery added for patients with single or few metastases. Because the potential late toxicity of WBRT is increasingly recognized when systemic tumor is more effectively controlled, there has been increased interest in the use of focal therapies such as radiosurgery with deferred WBRT even for patients with larger numbers of metastases. Although WBRT in combination with radiosurgery or surgical resection significantly reduces central nervous system recurrences at the treated site and elsewhere in the brain, it is not clear whether a patient's quality of life is more affected by tumor recurrence or by treatment with WBRT. In our practice, most patients with fewer than 7 to 10 tumors are treated with radiosurgery alone, with WBRT initially deferred because of concerns about its late toxicity. The ongoing technical improvements in radiosurgery have made this transition away from WBRT clinically feasible. This approach also allows patients to begin systemic therapy sooner, rather than waiting 2 to 4 weeks to complete WBRT. For patients with large or very symptomatic tumors, surgical resection is performed, followed by postoperative radiosurgery to the resection cavity, again initially deferring WBRT for many patients. This focal-only approach in the postoperative setting is associated with a higher rate of subdural dissemination and needs further prospective study, as some would argue that tumor progression is the major determinant of loss of function. Ultimately, better survival will require better systemic therapy that both controls extracranial disease and penetrates the brain to reduce intracranial recurrences. Unfortunately, many clinical trials of novel agents exclude patients with brain metastases.

Radiotherapy: Neurocognitive considerations in the treatment of brain metastases

The results of a randomized, controlled trial investigating the neurocognitive effects of stereotactic radiosurgery (SRS), with or without whole-brain radiation therapy (WBRT), to treat brain metastases demonstrated a significant reduction in learning and memory, associated with the addition of WBRT to SRS. the results indicate that SRS monotherapy is an effective and safe initial management strategy for brain metastases.

Renin-angiotensin system blockers and modulation of radiation-induced brain injury

Radiation-induced brain injury remains a major cause of morbidity in cancer patients with primary or metastatic brain tumors. Approximately 200,000 individuals/year are treated with fractionated partial or whole-brain irradiation, and > half will survive long enough (≤6 months) to develop radiation-induced brain injury, including cognitive impairment. Although short-term treatments have shown efficacy, no long-term treatments or preventive approaches are presently available for modulating radiation-induced brain injury. Based on previous preclinical studies clearly demonstrating that renin-angiotensin system (RAS) blockers can modulate radiation-induced late effects in the kidney and lung, we and others hypothesized that RAS blockade would similarly modulate radiation-induced brain injury. Indeed, studies in the last 5 years have shown that both angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II type 1 receptor antagonists (AT(1)RAs) can prevent/ameliorate radiation-induced brain injury, including cognitive impairment, in the rat. The mechanistic basis for this RAS blocker-mediated effect remains the subject of ongoing investigations. Putative mechanisms include, i] blockade of Ang II/NADPH oxidase-mediated oxidative stress and neuroinflammation, and ii] a change in the balance of angiotensin (Ang) peptides from the pro-inflammatory and pro-oxidative Ang II to the anti-inflammatory and anti-oxidative Ang-1-7). However, given that both ACEIs and AT(1)RAs are 1] well-tolerated drugs routinely prescribed for hypertension, 2] exhibit some antitumor properties, and 3] can prevent/ameliorate radiation-induced brain injury, they appear to be ideal drugs for future clinical trials, offering the promise of improving the quality of life of brain tumor patients receiving brain irradiation.

ACR Appropriateness Criteria: single brain metastasis

Single brain metastasis represents a common neurologic complication of cancer. Given the number of treatment options that are available for patients with brain metastasis and the strong opinions that are associated with each option, appropriate treatment for these patients has become controversial. Prognostic factors such as recursive partitioning analysis and graded prognostic assessment can help guide treatment decisions. Surgery, whole brain radiation therapy (WBRT), stereotactic radiosurgery or combination of these treatments can be considered based on a number of factors. Despite Class I evidence suggestive of best therapy, the treatment recommendation is quite varied among physicians as demonstrated by the American College of Radiology's Appropriateness Panel on single brain metastasis. Given the potential concerns of the neurocognitive effects of WBRT, the use of SRS alone or SRS to a resection cavity has gained support. Since aggressive local therapy is beneficial for survival, local control and quality of life, the use of these various treatment modalities needs to be carefully investigated given the growing number of long-term survivors. Enrollment of patients onto clinical trials is important to advance our understanding of brain metastasis.

Radiation dose and incidence of new metastasis in the anterior temporal lobe structures of radiosurgically treated patients

Object

Gamma Knife surgery (GKS) is frequently used to treat patients with metastasis to the brain. Radiosurgery seeks to limit radiation to the brain tissue surrounding the metastatic deposits. In patients with such lesions, a low radiation dose to the eloquent brain may help to prevent adverse effects. In this study the authors aimed to quantify the radiosurgical dose delivered to the anterior temporal structures in cases of metastatic brain lesions. They also evaluated the incidence and timing of new metastases in the anterior temporal lobes (ATLs) in patient cohorts that underwent GKS with or without whole-brain radiation therapy (WBRT).

Methods

The authors retrospectively analyzed 100 patients with metastatic brain lesions treated with GKS at the University of Virginia Health System. The anterior 5 cm of the temporal lobes and the hippocampi within the ATLs were contoured on the Gamma Knife planning station. Using the dose-volume histogram function in GammaPlan, treatment parameters for the metastases as well as radiation doses to the contoured ATLs and hippocampi were measured. Patients had clinical and MR imaging follow-ups at 3-month intervals. The ATLs and hippocampal regions were evaluated for the formation of new metastases on follow-up imaging.

Results

The demographic data—age, sex, Karnofsky Performance Scale score, number of temporal metastases at the time of GKS, total volume of metastatic tumors per patient, and number of intracranial metastatic deposits—were similar in the 2 cohorts. In patients without an ATL metastasis at the time of GKS, the mean maximum, 50% volume, and integral doses of radiation to the anterior temporal structures were very low: 2.6 Gy, 0.6 Gy, and 36.3 mJ in the GKS cohort and 2.1 Gy, 0.6 Gy, and 40.9 mJ in the GKS+WBRT cohort, respectively. Among the ATLs that had not shown a brain metastasis at the time of GKS, 8 of 92 temporal lobes in the GKS cohort and 10 of 89 in the GKS+WBRT cohort demonstrated a new anterior temporal lesion on follow-up MR imaging.

Conclusions

Gamma Knife surgery delivered a low dose of background radiation to the ATLs and hippocampi. The incidence of a new ATL metastasis in the GKS cohort was not higher than in the GKS+WBRT cohort. Gamma Knife surgery in the management of brain metastases limits the delivery of radiation to eloquent brain tissue without evidence of an appreciable propensity to develop new metastatic disease in the ATLs or hippocampi. This therapeutic approach may help to avoid unintended neurological dysfunction due to nonspecific delivery of radiation to eloquent brain tissues.

Control of brain metastases using frameless image-guided radiosurgery

Object

Radiosurgery is an important and well-accepted method in the management of brain metastases. Using conventional frame-based techniques, high lesional control rates are expected. The introduction of image-guided techniques allows for improved patient comfort and workflow. Some controversy exists as to the accuracy of imageguided techniques and consequently the impact they might have on control of brain metastases (as opposed to the level of control achieved with frame-based methods). The authors describe their initial 15-month experience with image-guided radiosurgery (IGRS) using Novalis with ExacTrac for management of brain metastases.

Methods

The authors reviewed the cases of brain metastasis treated by means of IGRS in their tertiary regional radiation oncology service over a 15-month period. During the study period 54 patients (median age 57.9 years) harboring 108 metastases were treated with IGRS. The median time from cancer diagnosis to development of brain metastasis was 12 months (range 0–144 months). The median tumor volume was 0.98 cm3 (range 0.03–19.07 cm3). The median prescribed dose was 18 Gy to the 80% isodose line (range 14–20 Gy). Lesions were followed with postradiosurgery MR imaging every 2–3 months following treatment.

Results

The median follow-up period was 9 months (range 0–20 months). Median actuarial survival was 8.6 months following IGRS. Eight patients with 18 lesions died within the first 2 months after the procedure, before scheduled follow-up imaging. Thus 90 lesions (in 46 patients) were followed up with imaging studies. Lesions that were unchanged or reduced in size were considered to be under control. The 6-month actuarial lesion control rate was 88%. Smaller lesions (< 1 cm3) had a statistically improved likelihood of complete imaging response (loss of all contrast-enhancement p = 0.01).

Conclusions

Image-guided radiosurgical treatment of brain metastases resulted in high rates of tumor control comparable to control rates reported for frame-based methods. High control rates were seen for small lesions in which spatial precision in dose delivery is critical. These data suggests that in regard to lesion control, IGRS using Novalis with ExacTrac is equivalent to frame-based radiosurgery methods.

Diagnosis-specific prognostic factors, indexes, and treatment outcomes for patients with newly diagnosed brain metastases: a multi-institutional analysis of 4,259 patients

PURPOSE

Controversy endures regarding the optimal treatment of patients with brain metastases (BMs). Debate persists, despite many randomized trials, perhaps because BM patients are a heterogeneous population. The purpose of the present study was to identify significant diagnosis-specific prognostic factors and indexes (Diagnosis-Specific Graded Prognostic Assessment [DS-GPA]).

METHODS AND MATERIALS

A retrospective database of 5,067 patients treated for BMs between 1985 and 2007 was generated from 11 institutions. After exclusion of the patients with recurrent BMs or incomplete data, 4,259 patients with newly diagnosed BMs remained eligible for analysis. Univariate and multivariate analyses of the prognostic factors and outcomes by primary site and treatment were performed. The significant prognostic factors were determined and used to define the DS-GPA prognostic indexes. The DS-GPA scores were calculated and correlated with the outcomes, stratified by diagnosis and treatment.

RESULTS

The significant prognostic factors varied by diagnosis. For non-small-cell lung cancer and small-cell lung cancer, the significant prognostic factors were Karnofsky performance status, age, presence of extracranial metastases, and number of BMs, confirming the original GPA for these diagnoses. For melanoma and renal cell cancer, the significant prognostic factors were Karnofsky performance status and the number of BMs. For breast and gastrointestinal cancer, the only significant prognostic factor was the Karnofsky performance status. Two new DS-GPA indexes were thus designed for breast/gastrointestinal cancer and melanoma/renal cell carcinoma. The median survival by GPA score, diagnosis, and treatment were determined.

CONCLUSION

The prognostic factors for BM patients varied by diagnosis. The original GPA was confirmed for non-small-cell lung cancer and small-cell lung cancer. New DS-GPA indexes were determined for other histologic types and correlated with the outcome, and statistical separation between the groups was confirmed. These data should be considered in the design of future randomized trials and in clinical decision-making.

Role of PPARs in Radiation-Induced Brain Injury

Whole-brain irradiation (WBI) represents the primary mode of treatment for brain metastases; about 200 000 patients receive WBI each year in the USA. Up to 50% of adult and 100% of pediatric brain cancer patients who survive >6 months post-WBI will suffer from a progressive, cognitive impairment. At present, there are no proven long-term treatments or preventive strategies for this significant radiation-induced late effect. Recent studies suggest that the pathogenesis of radiation-induced brain injury involves WBI-mediated increases in oxidative stress and/or inflammatory responses in the brain. Therefore, anti-inflammatory strategies can be employed to modulate radiation-induced brain injury. Peroxisomal proliferator-activated receptors (PPARs) are ligand-activated transcription factors that belong to the steroid/thyroid hormone nuclear receptor superfamily. Although traditionally known to play a role in metabolism, increasing evidence suggests a role for PPARs in regulating the response to inflammation and oxidative injury. PPAR agonists have been shown to cross the blood-brain barrier and confer neuroprotection in animal models of CNS disorders such as stroke, multiple sclerosis and Parkinson's disease. However, the role of PPARs in radiation-induced brain injury is unclear. In this manuscript, we review the current knowledge and the emerging insights about the role of PPARs in modulating radiation-induced brain injury.

NADPH oxidase mediates radiation-induced oxidative stress in rat brain microvascular endothelial cells

The need to both understand and minimize the side effects of brain irradiation is heightened by the ever-increasing number of patients with brain metastases that require treatment with whole brain irradiation (WBI); some 200,000 cancer patients/year receive partial or WBI. At the present time, there are no successful treatments for radiation-induced brain injury, nor are there any known effective preventive strategies. Data support a role for chronic oxidative stress in radiation-induced late effects. However, the pathogenic mechanism(s) involved remains unknown. One candidate source of reactive oxygen species (ROS) is nicotinamide adenosine dinucleotide phosphate (NADPH) oxidase, which converts molecular oxygen (O(2)) to the superoxide anion (O(2)(-)) on activation. We hypothesize that brain irradiation leads to activation of NADPH oxidase. We report that irradiating rat brain microvascular endothelial cells in vitro leads to increased (i) intracellular ROS generation, (ii) activation of the transcription factor NFkappaB, (iii) expression of ICAM-1 and PAI-1, and (iv) expression of Nox4, p22(phox), and p47(phox). Pharmacologic and genetic inhibition of NADPH oxidase blocked the radiation-mediated upregulation of intracellular ROS, activation of NFkappaB, and upregulation of ICAM-1 and PAI-1. These results suggest that activation of NADPH oxidase may play a role in radiation-induced oxidative stress.