Radiosurgery for brain metastases: relationship of dose and pattern of enhancement to local control

Factors associated with the local control of brain metastases: a systematic search and machine learning application

BACKGROUND

Enhancing Local Control (LC) of brain metastases is pivotal for improving overall survival, which makes the prediction of local treatment failure a crucial aspect of treatment planning. Understanding the factors that influence LC of brain metastases is imperative for optimizing treatment strategies and subsequently extending overall survival. Machine learning algorithms may help to identify factors that predict outcomes.

METHODS

This paper systematically reviews these factors associated with LC to select candidate predictor features for a practical application of predictive modeling. A systematic literature search was conducted to identify studies in which the LC of brain metastases is assessed for adult patients. EMBASE, PubMed, Web-of-Science, and the Cochrane Database were searched up to December 24, 2020. All studies investigating the LC of brain metastases as one of the endpoints were included, regardless of primary tumor type or treatment type. We first grouped studies based on primary tumor types resulting in lung, breast, and melanoma groups. Studies that did not focus on a specific primary cancer type were grouped based on treatment types resulting in surgery, SRT, and whole-brain radiotherapy groups. For each group, significant factors associated with LC were identified and discussed. As a second project, we assessed the practical importance of selected features in predicting LC after Stereotactic Radiotherapy (SRT) with a Random Forest machine learning model. Accuracy and Area Under the Curve (AUC) of the Random Forest model, trained with the list of factors that were found to be associated with LC for the SRT treatment group, were reported.

RESULTS

The systematic literature search identified 6270 unique records. After screening titles and abstracts, 410 full texts were considered, and ultimately 159 studies were included for review. Most of the studies focused on the LC of the brain metastases for a specific primary tumor type or after a specific treatment type. Higher SRT radiation dose was found to be associated with better LC in lung cancer, breast cancer, and melanoma groups. Also, a higher dose was associated with better LC in the SRT group, while higher tumor volume was associated with worse LC in this group. The Random Forest model predicted the LC of brain metastases with an accuracy of 80% and an AUC of 0.84.

CONCLUSION

This paper thoroughly examines factors associated with LC in brain metastases and highlights the translational value of our findings for selecting variables to predict LC in a sample of patients who underwent SRT. The prediction model holds great promise for clinicians, offering a valuable tool to predict personalized treatment outcomes and foresee the impact of changes in treatment characteristics such as radiation dose.

Predicting Survival with Brain Metastases in the Stereotactic Radiosurgery Era: are Existing Prognostic Scores Still Relevant? Or Can we do Better?

Predicting survival is essential to tailoring treatment for patients diagnosed with brain metastases. We have evaluated the performance of widely used, validated prognostic scoring systems (Graded Prognostic Assessment and diagnosis-specific Graded Prognostic Assessment) in over 1000 'real-world' patients treated with stereotactic radiosurgery to the brain, selected according to National Health Service commissioning criteria. Survival outcomes from our dataset were consistent with those predicted by the prognostic systems, but with certain cancer subtypes showing a significantly better survival than predicted. Although performance status remains the simplest tool for prediction, total brain tumour volume emerges as an independent prognostic factor, and a new, improved, prognostic scoring system incorporating this has been developed.

Clinical application of an institutional fractionated stereotactic radiosurgery (FSRS) program for brain metastases delivered with MRIdianⓇ BrainTx™

Single-fraction stereotactic radiosurgery (SRS) or fractionated SRS (FSRS) are well established strategies for patients with limited brain metastases. A broad spectrum of modern dedicated platforms are currently available for delivering intracranial SRS/FSRS; however, SRS/FSRS delivered using traditional CT-based platforms relies on the need for diagnostic MR images to be coregistered to planning CT scans for target volume delineation. Additionally, the on-board image guidance on traditional platforms yields limited inter-fraction and intra-fraction real-time visualization of the tumor at the time of treatment delivery. MR Linacs are capable of obtaining treatment planning MR and on-table MR sequences to enable visualization of the targets and organs-at-risk and may subsequently help identify anatomical changes prior to treatment that may invoke the need for on table treatment adaptation. Recently, an MR-guided intracranial package (MRIdian A3i BrainTxTM) was released for intracranial treatment with the ability to perform high-resolution MR sequences using a dedicated brain coil and cranial immobilization system. The objective of this report is to provide, through the experience of our first patient treated, a comprehensive overview of the clinical application of our institutional program for FSRS adaptive delivery using MRIdian's A3i BrainTx system-highlights include reviewing the imaging sequence selection, workflow demonstration, and details in its delivery feasibility in clinical practice, and dosimetric outcomes.

Cystic Brain Metastasis Outcomes After Gamma Knife Radiation Therapy

Purpose

The response of cystic brain metastases (BMets) to radiation therapy is poorly understood, with conflicting results regarding local control, overall survival, and treatment-related toxicity. This study aims to examine the role of Gamma Knife (GK) in managing cystic BMets.

Methods and Materials

Volumetric analysis was conducted to measure tumor and edema volume at the time of GK and follow-up magnetic resonance imaging studies. Survival was described using the Kaplan-Meier method, and the cumulative incidence of progression was described using the Aalen-Johansen estimator. We evaluated the association of 4 variables with survival using Cox regression analysis.

Results

Between 2016 and 2021, 54 patients with 83 cystic BMets were treated with GK at our institution. Lung cancer was the most common pathology (51.9%), followed by breast cancer (13.0%). The mean target volume was 2.7 cm3 (range, 0.1-39.0 cm3), and the mean edema volume was 13.9 cm3 (range, 0-165.5 cm3). The median prescription dose of single-fraction and fractionated GK was 20 Gy (range, 14-27.5 Gy). With a median follow-up of 8.9 months, the median survival time (MST) was 11.1 months, and the 1-year local control rate was 75.9%. Gamma Knife was associated with decreased tumor and edema volumes over time, although 68.5% of patients required steroids after GK. Patients whose tumors grew beyond baseline after GK received significantly more whole-brain radiation therapy (WBRT) before GK than those whose tumors declined after GK. Higher age at diagnosis of BMets and pre-GK systemic therapy were associated with worse survival, with an MST of 7.8 months in patients who received it compared with 23.3 months in those who did not.

Conclusions

Pre-GK WBRT may select for BMets with increased radioresistance. This study highlights the ability of GK to control cystic BMets with the cost of high posttreatment steroid use.

Predicting stereotactic radiosurgery outcomes with multi-observer qualitative appearance labelling versus MRI radiomics

Qualitative observer-based and quantitative radiomics-based analyses of T1w contrast-enhanced magnetic resonance imaging (T1w-CE MRI) have both been shown to predict the outcomes of brain metastasis (BM) stereotactic radiosurgery (SRS). Comparison of these methods and interpretation of radiomics-based machine learning (ML) models remains limited. To address this need, we collected a dataset of n = 123 BMs from 99 patients including 12 clinical features, 107 pre-treatment T1w-CE MRI radiomic features, and BM post-SRS progression scores. A previously published outcome model using SRS dose prescription and five-way BM qualitative appearance scoring was evaluated. We found high qualitative scoring interobserver variability across five observers that negatively impacted the model's risk stratification. Radiomics-based ML models trained to replicate the qualitative scoring did so with high accuracy (bootstrap-corrected AUC = 0.84-0.94), but risk stratification using these replicated qualitative scores remained poor. Radiomics-based ML models trained to directly predict post-SRS progression offered enhanced risk stratification (Kaplan-Meier rank-sum p = 0.0003) compared to using qualitative appearance. The qualitative appearance scoring enabled interpretation of the progression radiomics-based ML model, with necrotic BMs and a subset of heterogeneous BMs predicted as being at high-risk of post-SRS progression, in agreement with current radiobiological understanding. Our study's results show that while radiomics-based SRS outcome models out-perform qualitative appearance analysis, qualitative appearance still provides critical insight into ML model operation.

Stereotactic Radiosurgery of Multiple Brain Metastases: A Review of Treatment Techniques

The advancement of systemic targeted treatments has led to improvements in the management of metastatic disease, particularly in terms of survival outcomes. However, brain metastases remain less responsive to systemic therapies, underscoring the significance of local interventions for comprehensive disease control. Over the past years, the threshold for treating brain metastases through stereotactic radiosurgery has risen. Yet, as the number of treated metastases increases, treatment complexity and duration also escalate. This trend has made multi-isocenter radiosurgery treatments, such as those with the Gamma Knife, challenging to plan and lengthy for patients. In contrast, single-isocenter approaches employing linear accelerators offer an efficient and expeditious treatment option. This review delves into the literature, comparing different linear-accelerator-based techniques with each other and in relation to dedicated systems, focusing on dosimetric considerations and feasibility.

Comparison of Staged Stereotactic Radiosurgery and Fractionated Stereotactic Radiotherapy in Patients with Brain Metastases > 2 cm without Prior Whole Brain Radiotherapy: A Systematic Review and Meta-Analysis

OBJECTIVE

To compare fractionated stereotactic radiotherapy (FSRT) with staged stereotactic radiosurgery (SSRS) in patients with brain metastases >2 cm without prior whole brain radiotherapy.

METHODS

In this systematic review and meta-analysis, PubMed, Scopus, Web of Science, Embase, and Cochrane were searched to include studies that evaluated FSRT and/or SSRS for brain metastases >2 cm or 4 cm3 in adult patients with a known primary malignancy and no prior history of whole brain radiotherapy. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed and an indirect random-effect meta-analyses was conducted to compare treatment outcomes between the two modalities.

RESULTS

A total of 10 studies were included, comprising 612 (778 metastases) and 250 patients (265 metastases) in the SSRS and FSRT groups, respectively. The SSRS group had significantly older patients (66.6 ± 17.51 years vs. 62.37 ± 37.89 years; P = 0.029) with lower rate of control of primary disease (11.59% vs. 78.7%, P < 0.00001), and more patients with Karnofsky performance status ≥70 at baseline (92.81% vs. 88.56%; P = 0.045). FSRT was associated with a statistically nonsignificant but clinically important lower 12-month overall survival (44.75% [95% confidence interval [CI]: 30.48%-59.95%] vs. 53.25% [95%CI: 45.15%-61.19%], P = 0.1615) and higher rate of salvage radiotherapy (18.18% [95%CI: 8.75%-34%] vs. 12.27% [95%CI: 5.98%-23.53%], P = 0.0841). Both groups had comparable rates of local tumor control, mortality, tumor progression, recurrence, neurological death, and 6-month overall survival.

CONCLUSIONS

SSRS and FSRT were found to be comparable for treating brain metastases >2 cm not previously irradiated. Given the paucity of such studies, trials directly comparing the two treatment strategies are warranted to support these findings.

Pretreatment lymphocyte-to-monocyte ratio as a prognostic factor and influence on dose-effect in fractionated stereotactic radiotherapy for oligometastatic brain metastases in non-small cell lung cancer patients

Background

Studies on the prognostic factors for patients with brain oligo-metastasis treated with fractionated stereotactic radiotherapy (FSRT) usually focus on the size of metastatic tumor and radiation dose. Some inflammatory indicators have predictive value in non-small cell lung cancer (NSCLC) with brain metastasis receiving stereotactic radiotherapy. However, the prognostic value of inflammatory indicators in NSCLC patients with brain oligo-metastasis treated with FSRT, and their effect on radiotherapy dose is unknown.

Methods

A total of 95 advanced NSCLC patients with brain oligo-metastasis who had undergone FSRT treatment at Ningbo Medical Center Lihuili Hospital between January 2015 and April 2022 were enrolled into the study. Neutrophil to lymphocyte ratio (NLR), platelet lymphocyte ratio (PLR), lymphocyte to monocyte ratio (LMR), tumor diameter and biologically effective dose (BED10) were analyzed using Chi-square test. Univariate and multivariate Cox regressions were used to identify predictors of survival.

Results

Tumor diameter (< 2 cm), BED10 (≥ 48Gy) and LMR (≥ 4) were found to be independently associated with good intracranial local control survival (i-LCS) through multivariate analysis. The median i-LCS was longer in patients with 2 independent risk factors (tumor diameter ≥ 2 and LMR < 4) administered with BED10 > 53.6Gy compared with patients administered with BED10 ≤ 53.6Gy (20.7 months vs 12.0 months, P = 0.042). LMR ≥ 4 (P = 0.019) and positivity for driver gene mutations (P = 0.011) were independently associated with better overall survival (OS).

Conclusions

LMR is an independent prognostic factor of i-LCS and OS in NSCLC patients with brain oligo-metastasis treated with FSRT. Patients with tumor diameter ≥ 2 and LMR < 4 should be treated with BED10 greater than 53.6Gy.

Comparison of dosimetric parameters and robustness for rotational errors in fractionated stereotactic irradiation using automated noncoplanar volumetric modulated arc therapy for patients with brain metastases: single- versus multi-isocentric technique

To compare the dosimetric parameters of automated noncoplanar volumetric modulated arc therapy plans using single-isocentric (SIC) and multi-isocentric (MIC) techniques for patients with two brain metastases (BMs) in stereotactic irradiation and to evaluate the robustness of rotational errors. The SIC and MIC plans were retrospectively generated (35 Gy/five fractions) for 58 patients. Subsequently, a receiver operating characteristic curve analysis between the tumor surface distance (TSD) and V_25Gy was performed to determine the thresholds for the brain tissue. The SIC and MIC plans were recalculated based on the rotational images to evaluate the dosimetric impact of rotational error. The MIC plans showed better brain tissue sparing for TSD > 6.6 cm. The SIC plans provided a significantly better conformity index for TSD ≤ 6.6 cm, while significantly lower gradient index was obtained (3.22 ± 0.56vs. 3.30 ± 0.57, p < 0.05) in the MIC plans with TSD > 6.6 cm. For organs at risk (OARs) (brainstem, chiasm, lens, optic nerves, and retinas), D_0.1 cc was significantly lower (p < 0.05) in the MIC plans than in the SIC plans. The prescription dose could be delivered (D_99%) to the gross tumor volume (GTV) for patients with TSD ≤ 6.6 cm when the rotational error was < 1°, whereas 31% of the D_99% of GTV fell below the prescription dose with TSD > 6.6 cm. MIC plans can be an optimal approach for reducing doses to OARs and providing robustness against rotational errors in BMs with TSD > 6.6 cm.

Statistical Analysis on Time to Blindness of Glaucoma Patients at Jimma University Specialized Hospital: Application of Accelerated Failure Time Model

Background

Glaucoma is one of the most frequent vision-threatening eye diseases. It is frequently associated with excessive intraocular pressure (IOP), which can cause vision loss and damaged optic nerves. The main objective of this study was to model time to blindness of glaucoma patients by using appropriate statistical models. Study Design. A Retrospective Community-Based Longitudinal Study design was applied. Materials and Procedures. The data were obtained from Ophthalmology Department of JUSH from the period of January 2016 to August 2020. The glaucoma patient's information was extracted from the patient card and 321 samples were included in the study. To discover the factors that affect time to blindness of glaucoma patients', researchers used the Accelerated Failure Time (AFT) model.

Results

81.3 percent of the 321 glaucoma patients were blind. Unilaterally and bilaterally blinded female and male glaucoma patients were 24.92 and 56.38%, respectively. After glaucoma disease was confirmed, the median time to the blindness of both eyes and one eye was 12 months. The multivariable log-logistic accelerated failure-time model fits the glaucoma patient's time to blind dataset well. The result showed that the chance of blindness of glaucoma patients who have absolute stage of glaucoma, medium duration of diagnosis, long duration of diagnosis, and IOP greater than 21 mmHg were high with parameters (ϕ = 2.425, p value = 0.049, 95% CI [2.249, 2.601]), (ϕ = 1.505, p value = 0.001, 95% CI [0.228, 0.589]), (ϕ = 3.037, p value = 0.001, 95% C.I [2.850, 3.22]) and (ϕ 0.851, p value = 0.034, 95% C.I [0.702, 0.999]), respectively.

Conclusion

The multivariable log-logistic accelerated failure time model evaluates the prognostic factors of time to blindness of glaucoma patients. Under this finding, duration of diagnosis, IOP, and stage of glaucoma were a key determinant factors of time to blindness of glaucoma patients'. Finally, the log-logistic accelerated failure-time model was the best-fitted parametric model based on AIC and BIC values.

Dose-Response Effect and Dose-Toxicity in Stereotactic Radiotherapy for Brain Metastases: A Review

Simple Summary

Brain metastases are one of the most frequent complications for cancer patients. Stereotactic radiosurgery is considered a cornerstone treatment for patients with limited brain metastases and the ideal dose and fractionation schedule still remain unknown. The aim of this literature review is to discuss the dose-effect relation in brain metastases treated by stereotactic radiosurgery, accounting for fractionation and technical considerations.

Abstract

For more than two decades, stereotactic radiosurgery has been considered a cornerstone treatment for patients with limited brain metastases. Historically, radiosurgery in a single fraction has been the standard of care but recent technical advances have also enabled the delivery of hypofractionated stereotactic radiotherapy for dedicated situations. Only few studies have investigated the efficacy and toxicity profile of different hypofractionated schedules but, to date, the ideal dose and fractionation schedule still remains unknown. Moreover, the linear-quadratic model is being debated regarding high dose per fraction. Recent studies shown the radiation schedule is a critical factor in the immunomodulatory responses. The aim of this literature review was to discuss the dose–effect relation in brain metastases treated by stereotactic radiosurgery accounting for fractionation and technical considerations. Efficacy and toxicity data were analyzed in the light of recent published data. Only retrospective and heterogeneous data were available. We attempted to present the relevant data with caution. A BED10 of 40 to 50 Gy seems associated with a 12-month local control rate >70%. A BED10 of 50 to 60 Gy seems to achieve a 12-month local control rate at least of 80% at 12 months. In the brain metastases radiosurgery series, for single-fraction schedule, a V12 Gy < 5 to 10 cc was associated to 7.1–22.5% radionecrosis rate. For three-fractions schedule, V18 Gy < 26–30 cc, V21 Gy < 21 cc and V23 Gy < 5–7 cc were associated with about 0–14% radionecrosis rate. For five-fractions schedule, V30 Gy < 10–30 cc, V 28.8 Gy < 3–7 cc and V25 Gy < 16 cc were associated with about 2–14% symptomatic radionecrosis rate. There are still no prospective trials comparing radiosurgery to fractionated stereotactic irradiation.

Single- and hypofractionated stereotactic radiosurgery for large (> 2 cm) brain metastases: a systematic review

PURPOSE

Since frameless stereotactic radiosurgery (SRS) techniques have been recently introduced, hypofractionated SRS (HF-SRS) for large brain metastases (BMs) is gradually increasing. To verify the efficacy and safety of HF-SRS for large BMs, we aimed to perform a systematic review and compared them with SF-SRS.

METHODS

We systematically searched the studies regarding SF-SRS or HF-SRS for large (> 2 cm) BM from databases including PubMed, Embase, and the Cochrane Library on July 31, 2018. Biologically effective dose with the α/β ratio of 10 (BED₁₀), 1-year local control (LC), and radiation necrosis (RN) were compared between the two groups, with the studies being weighted by the sample size.

RESULTS

The 15 studies with 1049 BMs that described 1-year LC and RN were included. HF-SRS tended to be performed in larger tumors; however, higher mean BED₁₀ (50.1 Gy₁₀ versus 40.4 Gy₁₀, p < 0.0001) was delivered in the HF-SRS group, which led to significantly improved 1-year LC (81.6 versus 69.0%, p < 0.0001) and 1-year overall survival (55.1 versus 47.2%, p < 0.0001) in the HF-SRS group compared to the SF-SRS group. In contrast, the incidence of radiation toxicity was significantly decreased in the HF-SRS group compared to the SF-SRS group (8.0 versus 15.6%, p < 0.0001).

CONCLUSION

HF-SRS results in better LC of large BMs while simultaneously reducing RN compared to SF-SRS. Thus, HF-SRS should be considered a priority for SF-SRS in patients with large BMs who are not suitable to undergo surgical resection.

Tuning-Target-Guided Inverse Planning of Brain Tumors With Abutting Organs at Risk During Gamma Knife Stereotactic Radiosurgery

Purpose We proposed a planning strategy that utilized tuning targets to guide GammaKnife (GK) Inverse Planning (IP) to deliver higher dose to the tumor, while keeping acceptable dose to the abutting organ at risk (OAR). Methods Ten patients with a large portion of brain tumor abutting the OAR previously treated with GK stereotactic radiosurgery (SRS) were selected. For each patient, multiple tuning targets were created by cropping the target contour from three-dimensional (3D) expansions of the OAR. The number of the tuning targets depended on the complexity of the planning process. To demonstrate dose sparing effect, an IP plan was generated for each tuning target after one round of optimization without shot fine-tuning. In the dose enhancement study, a more aggressive target dose was prescribed to the tuning target with a larger margin and one to two shots were filled in the region with missing dose. The resulting plans were compared to the previously approved clinical plans. Results For all 10 patients, a dose sparing effect was observed, i.e. both target coverage and dose to the OARs decreased when the margins of 3D expansion increased. For one patient, a margin of 6 mm was needed to decrease the maximum dose to the optical chiasm and optical nerve by 44.3% and 28.4%, respectively. For the other nine patients, the mean dropping rate of V12Gyto brain stem were 28.2% and 59.5% for tuning targets of 1 and 2 mm margins, respectively. In the dose enhancement study, the tuning-target-guided plans were hotter than the approved treatment plans, while keeping similar dose to the OARs. The mean of the treatment and enhancement dose was 15.6 ± 2.2 Gy and 18.5 ± 3.2 Gy, respectively. The mean coverage of the target by prescription dose was slightly higher in the enhancement plans (96.9 ± 2.6% vs 96.3 ± 3.6%), whereas the mean coverage of the enhancement dose was 20.1% higher in the enhancement plans (89.6 ± 9.0% vs 74.6 ± 19.9%). Conclusions We demonstrated that an inverse planning strategy could facilitate target dose enhancement for challenging GK cases while keeping acceptable OAR dose.

Comparison of two-stage Gamma Knife radiosurgery outcomes for large brain metastases among primary cancers

PURPOSE

Stereotactic radiosurgery (SRS) is typically considered for patients who cannot undergo surgical resection for large (> 10 cm³) brain metastases (BMs). Staged SRS requires adaptive planning during each stage of the irradiation period for improved tumor control and reduced radiation damage. However, there has been no study on the tumor reduction rates of this method. We evaluated the outcomes of two-stage SRS across multiple primary cancer types.

METHODS

We analyzed 178 patients with 182 large BMs initially treated with two-stage SRS. The primary cancers included breast (BC), non-small cell lung (NSCLC), and gastrointestinal tract cancers (GIC). We analyzed the overall survival (OS), neurological death, systemic death (SD), tumor progression (TP), tumor recurrence (TR), radiation necrosis (RN), and the tumor reduction rate during both stages.

RESULTS

The median survival time after the first Gamma Knife surgery (GKS) procedure was 6.6 months. Compared with patients with BC and NSCLC, patients with GIC had shorter OS and a higher incidence of SD. Compared with patients with NSCLC and GIC, patients with BC had significantly higher tumor reduction rates in both sessions. TP rates were similar among primary cancer types. There was no association of the tumor reduction rate with tumor control. The overall cumulative incidence of RN was 4.2%; further, the RN rates were similar among primary cancer types.

CONCLUSIONS

Two-stage SRS should be considered for BC and NSCLC if surgical resection is not indicated. For BMs from GIC, staged SRS should be carefully considered and adapted to each unique case given its lower tumor reduction rate and shorter OS.

Two-staged stereotactic radiosurgery for the treatment of large brain metastases: Single institution experience and review of literature

Introduction: Two-staged stereotactic radiosurgery (SRS) has been shown as an effective treatment for brain metastases that are too large for single fraction SRS. Methods: Patients with large brain metastases (>4 cm³) treated with two-staged SRS from January 2017 to December 2019 at our institution were retrospectively identified. Results: There were 23 brain metastases treated. The normal brain volume receiving equivalent 12Gy-in-single-fraction was defined as V_12E. The V_12E for original single-fraction GKS plan (mean of 41.4 cm³, range 5.6-146.1 cm³) was significantly higher compared to that of the second stage (mean of 23.7 cm³, range 2.8-92.7 cm³). The median tumor volume measured at the second stage (4.30 cm³) was reduced by an average of 52.2% compared to the first stage (9.58 cm³). Three patients (27.3%) showed local tumor progression in 4 tumors (20%). The median time to progression was 152 days. Conclusions: Two-staged SRS is an effective treatment technique for large brain metastasis that results in significant reduction of tumor volume at the second stage SRS. Optimal treatment dose has not yet been defined.

Superior Prognostic Value of Cumulative Intracranial Tumor Volume Relative to Largest Intracranial Tumor Volume for Stereotactic Radiosurgery-Treated Brain Metastasis Patients

BACKGROUND

Two intracranial tumor volume variables have been shown to prognosticate survival of stereotactic-radiosurgery-treated brain metastasis patients: the largest intracranial tumor volume (LITV) and the cumulative intracranial tumor volume (CITV).

OBJECTIVE

To determine whether the prognostic value of the Scored Index for Radiosurgery (SIR) model can be improved by replacing one of its components-LITV-with CITV.

METHODS

We compared LITV and CITV in terms of their survival prognostication using a series of multivariable models that included known components of the SIR: age, Karnofsky Performance Score, status of extracranial disease, and the number of brain metastases. Models were compared using established statistical measures, including the net reclassification improvement (NRI > 0) and integrated discrimination improvement (IDI). The analysis was performed in 2 independent cohorts, each consisting of ∼3000 patients.

RESULTS

In both cohorts, CITV was shown to be independently predictive of patient survival. Replacement of LITV with CITV in the SIR model improved the model's ability to predict 1-yr survival. In the first cohort, the CITV model showed an NRI > 0 improvement of 0.2574 (95% confidence interval [CI] 0.1890-0.3257) and IDI of 0.0088 (95% CI 0.0057-0.0119) relative to the LITV model. In the second cohort, the CITV model showed a NRI > 0 of 0.2604 (95% CI 0.1796-0.3411) and IDI of 0.0051 (95% CI 0.0029-0.0073) relative to the LITV model.

CONCLUSION

After accounting for covariates within the SIR model, CITV offers superior prognostic value relative to LITV for stereotactic radiosurgery-treated brain metastasis patients.

Les métastases cérébrales de cancer du rein, un défi clinique

BRAIN METASTASES IN RENAL CELL CARCINOMA, AN UNMET NEED

Brain metastases from renal cell carcinomas are associated with dismal prognosis and might be present in up to 10 % of metastatic patients. Biologically, the blood brain barrier might be disrupted in brain metastases and thus do not exclusively account for treatment resistance. Brain metastases often acquire additional molecular alterations that might provide aggressive features. They are also associated with high lymphocytic infiltration and expression of immune checkpoints PD-1/PD-L1. In clinical routine, scores based on metastatic volume and patients' performance status might help better predict survival. The cornerstone of brain metastases treatment is stereotactic radiation therapy if patients are eligible, while systemic treatments such as antiangiogenics and immune checkpoint inhibitors only provide limited disease control. Early identification of patients with brain metastases from renal cell carcinomas and promotion of dedicated clinical trials will be important to try and improve current clinical management.

Surgical resection and postoperative radiosurgery versus staged radiosurgery for large brain metastases

PURPOSE

The purpose of this study was to retrospectively evaluate the new treatment paradigm of staged stereotactic radiosurgery (SRS) for the treatment of large brain metastases (BM) compared to the standard of surgical resection followed by SRS.

METHODS

We evaluated 78 patients with large BM treated 2012-2017 with surgical resection and postoperative SRS (surgery + SRS) or staged SRS separated by 1 month. Overall survival (OS) was estimated using the Kaplan Meier method and compared across groups using the log-rank test. Cumulative incidence of neurologic death and local and distant brain failure (LF, DBF) were estimated using competing risk methodology.

RESULTS

Forty patients were treated with surgery + SRS and 38 patients were treated with staged SRS. Median follow-up was 23.2 months (95% CI 20.5-39.3). Median OS was 13.2 months for staged SRS compared to surgery + SRS 9.7 months (p = 0.53). Cumulative incidence of neurologic death at 1 year was 23% after surgery + SRS, 27% after staged SRS (p = 0.69); cumulative incidence of LF at 1 year was 6% and 8% (p = 0.65) and 1-year DBF was 59% and 21% (p ≤ 0.01). Overall rates of leptomeningeal failure and radiation necrosis were similar between the groups (p = 0.63 and p = 1.0).

CONCLUSIONS

Though surgery and postoperative SRS is the standard, staged SRS represents an attractive treatment paradigm for treating large BM without sacrificing LC or survival, and potentially decreases DBF. Prospective studies are needed to validate these findings.

Hypofractionated stereotactic radiotherapy for oligometastatic patients: developing of a response predictive model

OBJECTIVES

Treatment of oligometastatic patients is a current challenge in radiation oncology. Aim of this study is to define a dose-response relationship for hypofractionated radiotherapy of oligometastases.

METHODS

Retrospective analysis of metastases treated by hypofractionated stereotactic radiotherapy was performed. Delivered dose was calculated both as biological effective dose (BED₁₀), and as ratio between BED₁₀ and the logarithm of metastasis volume (BED₁₀ logVolume Ratio, BVR). Two dose-response models were defined by logistic regression. The fitted outcome was the Metastases Complete Response (MCR). Performances of the models were assessed by area under the receiver operating curve (AUC) and by bootstrap calibration of original data. BED₁₀ and BVR impact on survival outcomes has been evaluated.

RESULTS

Fifty-three patients with 79 metastases were analyzed. AUC and calibration of BVR-based logistic model showed better accuracy in predicting MCR with respect to BED₁₀-based model. No significant difference between the two ROCs was observed (De Long test p value > 0.05), but significant discordance in calibration resulted in the BED₁₀ model (p value < 0.05 in Hosmer-Lemeshow Goodness of fit test). BVR returned also better results in multivariate analyses for survival outcomes.

CONCLUSIONS

The ratio between BED₁₀ and the logarithm of metastasis volume (BVR), as a corrective factor for fitting the probability of metastases response to stereotactic radiotherapy, could be a tool for evaluating and prescribing treatments for oligometastatic disease. BVR can be useful for producing more reliable survival statistics too.

Staged Stereotactic Radiosurgery for Large Brain Metastases: Local Control and Clinical Outcomes of a One-Two Punch Technique

BACKGROUND

Treatment options are limited for large, unresectable brain metastases.

OBJECTIVE

To report a single institution series of staged stereotactic radiosurgery (SRS) that allows for tumor response between treatments in order to optimize the therapeutic ratio.

METHODS

Patients were treated with staged SRS separated by 1 mo with a median dose at first SRS of 15 Gy (range 10-21 Gy) and a median dose at second SRS of 14 Gy (range 10-18 Gy). Overall survival was evaluated using the Kaplan-Meier method. Cumulative incidences were estimated for neurological death, radiation necrosis, local failure (marginal or central), and distant brain failure. Absolute cumulative dose-volume histogram was created for each treated lesion. Logistic regression and competing risks regression were performed for each discrete dose received by a certain volume.

RESULTS

Thirty-three patients with 39 lesions were treated with staged radiosurgery. Overall survival at 6 and 12 mo was 65.0% and 60.0%, respectively. Cumulative incidence of local failure at 6 and 12 mo was 3.2% and 13.3%, respectively. Of the patients who received staged therapy, 4 of 33 experienced local failure. Radiation necrosis was seen in 4 of 39 lesions. Two of 33 patients experienced a Radiation Therapy Oncology Group toxicity grade > 2 (2 patients had grade 4 toxicities). Dosimetric analysis revealed that dose (Gy) received by volume of brain (ie, VDose(Gy)) was associated with radiation necrosis, including the range V44.5Gy to V87.8Gy.

CONCLUSION

Staged radiosurgery is a safe and effective option for large, unresectable brain metastases. Prospective studies are required to validate the findings in this study.

HyperArc VMAT planning for single and multiple brain metastases stereotactic radiosurgery: a new treatment planning approach

Purpose

The HyperArc VMAT (HA-VMAT) planning approach was newly developed to fulfill the demands of dose delivery for brain metastases stereotactic radiosurgery. We compared the dosimetric parameters of the HA-VMAT plan with those of the conventional VMAT (C-VMAT).

Material and methods

For 23 patients (1–4 brain metastases), C-VMAT and HA-VMAT plans with a prescription dose of 20–24 Gy were retrospectively generated, and dosimetric parameters for PTV (homogeneity index, HI; conformity index, CI; gradient index, GI) and brain tissue (V_2Gy-V_16Gy) were evaluated. Subsequently, the physical characteristics (modulation complexity score for VMAT, MCSV; Monitor unit, MU) of both treatment approaches were compared.

Results

HA-VMAT provided higher HI (1.41 ± 0.07 vs. 1.24 ± 0.07, p < 0.01), CI (0.93 ± 0.02 vs. 0.90 ± 0.05, p = 0.01) and lower GI (3.06 ± 0.42 vs. 3.91 ± 0.55, p < 0.01) values. Moderate-to-low dose spreads (V_4Gy-V_16Gy) were significantly reduced (p < 0.01) in the HA-VMAT plan over that of C-VMAT. HA-VMAT plans resulted in more complex MLC patterns (lower MCSV, p < 0.01) and higher MU (p < 0.01).

Conclusions

HA-VMAT plans provided significantly higher conformity and rapid dose falloff with respect to the C-VMAT plans.

Internal dose escalation is associated with increased local control for non-small cell lung cancer (NSCLC) brain metastases treated with stereotactic radiosurgery (SRS)

Objective

To identify potentially actionable dosimetric predictors of local control (LC) for non-small cell lung cancer (NSCLC) brain metastases treated with single-fraction stereotactic radiosurgery (SRS).

Methods and materials

Patients with NSCLC brain metastases treated with single-fraction SRS were identified. Eligible patients had at least 1 follow-up magnetic resonance imaging scan and were without prior metastasectomy or SRS to the same lesion. LC and overall survival (OS) were estimated using the Kaplan-Meier method. The Cox proportional hazards model was used for univariate (UVA) and multivariate analysis (MVA). Receiver operating characteristic (ROC) analysis was used to identify optimal cut points for dose-volume histogram metrics relative to LC.

Results

A total of 612 NSCLC brain metastasis were identified in 299 patients with single-fraction SRS between 1999 and 2014. Median follow-up was 10 months. Median OS from time of SRS was 11 months. Overall LC was 75% and 66% at 1 and 2 years, respectively. On UVA, increasing dose by any measure was associated with improved LC. On MVA, volume receiving at least 32 Gy (V32; hazard ratio [HR], 0.069; P < .000), along with higher prescription isodose (HR, 0.953; P = .031) and lower volume (HR, 1.359; P < .000), were independent predictors of improved LC. ROC analysis demonstrated a V32 of 24% to be most predictive for LC. For the entire cohort, 1-year LC for V32 ≥24% was 89% versus 67% for V32 <24% (P = .000). Stratifying by volume, lesions ≤2 cm (n = 323) had a 1-year LC of 95% versus 82% (P = .005) for V32 above and below 24%, respectively. For lesions 2.1 to 3 cm (n = 211), 1-year LC was 79% versus 59% (P = .003) for V32 above and below 24%, respectively. Total tumor volume alone was predictive for OS.

Conclusions

Volume, prescription isodose line, and V32 are independent predictors of LC. V32 represents an actionable SRS treatment planning parameter for NSCLC brain metastases.

Clinical outcomes of patients with limited brain metastases treated with hypofractionated (5×6Gy) conformal radiotherapy

BACKGROUND AND PURPOSE

Hypofractionated conformal radiotherapy (hfCRT) is used for larger brain metastases or metastases near critical structures. We investigated hfCRT outcomes for newly diagnosed brain metastases.

MATERIALS AND METHODS

We identified 195 patients with 1-3 brain metastases who underwent 5×6Gy hfCRT for 231 lesions from 2007 to 2013. Associations among clinical factors, local control (LC), distant brain control (DC) and overall survival (OS) were tested using univariate and multivariate (MVA) Cox regression analysis and Kaplan-Meier method.

RESULTS

Median follow-up was 12.8months. One hundred forty-three (62%) lesions were treated with hfCRT post-operatively, and 88 (38%) with definitive hfCRT. LC for all lesions was 83% at 1year. For lesions treated with post-operative hfCRT, tumor size (HR=4.7, p=0.04) and subtotal resection (HR=2.7, p=0.02) were predictive of local failure on MVA. For lesions ≥2.8cm in size, LC was 61% at 12months for lesions status-post subtotal resection, compared to 84% status-post gross total resection (p=0.004). Extracranial disease presence was associated with worse DC (HR=1.8, p=0.008) and OS (HR=3.1, p<0.001).

CONCLUSIONS

We showed 5×6Gy hfCRT provides acceptable LC at 1year for limited brain metastases. For large lesions not grossly resected, more aggressive strategies can be considered to improve LC.

Five-fraction stereotactic radiosurgery (SRS) for single inoperable high-risk non-small cell lung cancer (NSCLC) brain metastases

BACKGROUND

Achieving durable local control while limiting normal tissue toxicity with definitive radiation therapy in the management of high-risk brain metastases remains a radiobiological challenge. The objective of this study was to examine the local control and toxicity of a 5-fraction stereotactic radiosurgical approach for treatment of patients with inoperable single high-risk NSCLC brain metastases.

METHODS

This retrospective analysis examines 20 patients who were deemed to have "high-risk" brain metastases. High-risk tumors were defined as those with a maximum diameter greater than 2 cm and/or those located within an eloquent cortex. Patients were evaluated by a neurosurgeon prior to treatment and determined to be inoperable due to tumor or patient characteristics. Patients were treated using the CyberKnife® SRS system in 5 fractions to a total dose of 30 Gy, 35 Gy, or 40 Gy.

RESULTS

Twenty patients with a median age of 65.5 years were treated from April 2010 to August 2014 in 5 fractions to a median total dose of 35 Gy. At a median follow up of 11.3 months local tumor control was observed in 18 of 20 metastases (90 %). Both local failures were observed in patients receiving a lower dose of 30 Gy. Median pre-treatment dexamethasone dose was 10 mg/day and median post-treatment nadir dose was 0 mg/day. Salvage intracranial therapy was required in 45 % of patients. Symptomatic radionecrosis was observed in 4 of 20 patients (20 %), two of which were treated to 40 Gy and the remainder to 35 Gy. Kaplan-Meier 1-year, 2-year, and median survival were calculated to be 45 %, 20 %, and 13.2 months, respectively.

CONCLUSIONS

Five-fraction SRS to a total dose of 35 Gy appears to be a safe and effective management strategy for single high-risk NSCLC brain metastases, while a total dose of 40 Gy leads to an excess risk of neurotoxicity.

Gamma Knife radiosurgery for cystic brain metastases

OBJECTIVE

The goal of this study was to investigate the treatment results of Gamma Knife radiosurgery (GKRS) for cystic brain metastases and relevant factors associated with local tumor control.

MATERIALS AND METHODS

We retrospectively reviewed the clinical, radiological, and dosimetry data of 37 cystic brain metastases of 28 patients who were treated with GKRS. Cyst drainage was performed in 8 large lesions before GKRS to decrease the target volume. The mean target volume was 4.8 (range, 0.3-15.8) cc at the time of GKRS, and the mean prescription dose was 16.6 (range, 13-22) Gy.

RESULTS

The actuarial median survival time was 17.7 ± 10.2 months, and the primary tumor status was a significant prognostic factor for survival. The actuarial local tumor control rate at 6 and 12 months was 93.1 and 82.3%, respectively. Among the various factors, only prescription dose (>15 Gy) was a significant factor related to local tumor control after multivariate analysis (p = 0.049). Cyst volume or cyst/total tumor volume ratio did not influence local control after GKRS, when the target volume was reduced to about 15 cc after cyst drainage.

CONCLUSION

According to our results, we suggest that stereotactic radiosurgery should be considered as one of the treatment options for cystic brain metastases, when large tumor volume can be reduced by surgical drainage before radiosurgery, especially for patients with a controlled primary tumor.

Tumor resection with carmustine wafer placement as salvage therapy after local failure of radiosurgery for brain metastasis

Prolonged survival in brain metastasis patients increases recurrence rates and places added importance on salvage therapies. Research examining carmustine polymer wafers as an adjuvant therapy for brain metastasis is limited. We present a single institution retrospective series documenting the use of BCNU wafers placed in the cavity of resected recurrent brain metastases that had failed prior stereotactic radiosurgery (SRS). Between February 2002 and April 2013, a total of 31 patients with brain metastases failed SRS and underwent resection with intracavitary placement of carmustine wafers. Clinical outcomes including local control, survival, cause of death, and toxicity were determined from electronic medical records. Kaplan-Meier analysis was performed to assess local control and survival. Imaging features were reviewed and described for patients with serial post-operative follow-up imaging examinations over time. Overall survival at 6 months and 12 months was 63% and 36%, respectively. Fourteen of 31 patients (45%) died from neurologic causes. Local control within the resection cavity was 87% and 70% at 6 and 12 months, respectively. Five patients (16%) underwent further salvage therapy following carmustine wafer placement after local failure. Resection cavities of all six patients with follow-up imaging showed linear peripheral enhancement. Pericavity and wafer enhancement was present as early as the same day as surgery and persisted in all cases to 6 months or longer. Carmustine polymer wafers are an effective salvage treatment following resection of a brain metastasis that has failed prior SRS. For patients with successful local control after wafer implantation, linear enhancement at the cavity is common.

Use of Helical TomoTherapy for the Focal Hypofractionated Treatment of Limited Brain Metastases in the Initial and Recurrent Setting

Background: Whole-brain radiation therapy (WBRT), stereotactic radiosurgery (SRS), or both are commonly employed in the treatment of limited brain metastases in the initial or recurrent setting. Hypofractionated partial volume irradiation is also employed, however, published experience using helical TomoTherapy (HT) for this purposes is limited. We reviewed our institutional experience to assess patient selection factors, fractionation scheme, and outcomes associated with this technique.

Methods: A retrospective chart review was performed to evaluate patients treated with partial volume hypofractionated HT-based IMRT for brain metastases at our institution.

Results: Thirteen patients (7M/6F, median age 62, median KPS 90) with a limited (1–9) number of brain metastases in the primary or recurrent setting were identified. Primary malignancies included colorectal (3), NSCLC (5), RCC (1), breast (1), melanoma (1), uterine (1), and ovarian (1). The median time from initial diagnosis to brain metastases was 20.7 months (range 0–61.3). Treatment was delivered to intact metastases in six patients, to a single resection cavity in six patients, and to both in one patient. A total of 27 lesions were treated. The median number of intact metastases treated was two (range 1–9). Previous treatments included WBRT (5), WBRT + SRS (3), SRS alone (1), and none (4). The most common fractionation schemes were 25 Gy in five fractions and 27.5 Gy in five fractions to each lesion. At a median of 6 months follow up (range 1.26–20.13) after TomoTherapy, 10 patients were deceased, 2 were alive, and 1 was lost to follow up. Systemic progression occurred in seven patients and intracranial progression occurred in five. The median intracranial progression free survival and overall survival after TomoTherapy was 6.3 months. Freedom from local failure for treated lesions was 71% and 59% at 6 and 12 months.

Conclusion: TomoTherapy-based hypofractionated radiotherapy to a limited number of metastatic lesions is associated with acceptable intracranial disease control and survival outcomes and represents a viable treatment option in the primary and recurrent setting for select patients.

Chemotherapy and biological treatment options in breast cancer patients with brain metastasis: an update

INTRODUCTION

Breast cancer (BC) is the second most common cause of CNS metastasis. Ten to 20% of all, and 38% of human epidermal growth factor-2(+), metastatic BC patients experience brain metastasis (BM). Prolonged survival with better control of systemic disease and limited penetration of drugs to CNS increased the probability of CNS metastasis as a sanctuary site of relapse. Treatment of CNS disease has become an important component of overall disease control and quality of life.

AREAS COVERED

Current standard therapy for BM is whole-brain radiotherapy, surgery, stereotactic body radiation therapy for selected cases, corticosteroids and systemic chemotherapy. Little progress has been made in chemotherapy for the treatment of BM in patients with BC. Nevertheless, new treatment choices have emerged. In this review, we aimed to update current and future treatment options in systemic treatment for BM of BC.

EXPERT OPINION

Cornerstone local treatment options for BM of BC are radiotherapy and surgery in selected cases. Efficacy of cytotoxic chemotherapeutics is limited. Among targeted therapies, lapatinib has activity in systemic treatment of BM particularly when used in combination with capecitabine. Novel agents are currently investigated.

Stereotactic radiosurgery for 318 brain metastases in a single Australian centre: the impact of histology and other factors

While melanoma brain metastases (BM) are consistently associated with worse survival compared to other histologies, whether they correlate with worse local control (LC) following stereotactic radiosurgery (SRS) is not yet well-defined. In this study of prospectively and retrospectively collected data we investigated the impact of histology and other host, tumour and treatment factors on overall survival (OS) and LC. We analysed 162 patients and 318 BM lesions from various histologies treated with SRS between 2005 and 2011. We included patients who received SRS as first-line treatment, as well as patients who received SRS for residual or recurrent BM following prior surgery, whole brain radiotherapy (WBRT) or both. Median OS for the entire cohort was 8.4 months. Median OS for tumour histologies of melanoma, lung and breast cancer were 5.1, 12.2, and 14.7 months, respectively. On multivariate analysis, melanoma predicted for worse OS (hazard ratio [HR] 1.515, p = 0.003) together with performance status (HR 1.662, p < 0.001) and uncontrolled systemic disease (HR 1.755, p = 0.003). Melanoma histology was also negatively predictive for LC (HR 1.828, p = 0.021) together with increasing tumour size (HR 1.038, p = 0.017). Other factors, including the use of WBRT with SRS, the use of planning treatment volume margins, and prescription dose were not significantly predictive for OS and LC. We conclude melanoma histology also portends poorer LC in the SRS setting. While survival depends significantly on the systemic behaviour of the disease, treatment refinements to reduce local failure still merit exploration, especially in the era of targeted therapies.

Alternative treatment of stereotactic cyst aspiration and radiosurgery for cystic brain metastases

BACKGROUND

Surgical removal is the first choice of treatment for large cystic brain metastases. However, some patients cannot undergo surgical resection due to their general condition and/or the tumor location.

AIMS

In this study, we investigated the feasibility and safety of stereotactic cyst aspiration and gamma knife radiosurgery (GKR) as an alternative treatment for these lesions and followed the volumetric changes in cystic and solid portions.

METHODS

Between February 2005 and March 2012, a total of 24 patients underwent GKR after cyst aspiration for 29 cystic metastatic brain tumors. The median age was 60 years (range, 18-81). The number of male patients was 18 and that of female patients 6. Most of the patients were in class II (87.5%) based on the data of the Radiation Therapy Oncology Group using recursive partitioning analysis. We analyzed the changes in tumor volume, the local control rate, intracranial progression-free survival (PFS) and overall survival (OS).

RESULTS

Before aspiration, the mean total tumor volume was 32.7 cm(3) (range, 12.1-103.3) and cystic volume was 18.6 cm(3) (range, 8-72.3). The mean duration of cyst drainage was 1 day (range, 1-2). The mean amount of aspiration was 16.8 cm(3) (range, 6-67.4). After aspiration, the total mean volume was 12.4 cm(3) (range, 3.7-38.1) and cystic volume was 2.0 cm(3) (range, 0.1-9.5). The nature of the cyst was serous in 18, serous and hemorrhagic in 3, and serous and necrotic in 8. The median prescription dose was 16 Gy (range, 14-20). There was no treatment-related complication. The local control rate was 58.6% (17/29). The median survival to local recurrence was 6.0 (±1.42) months. During the follow-up period, an Ommaya reservoir was placed in 3 patients. Insertion of an Ommaya reservoir and whole-brain radiotherapy (WBRT) or GKR were done in 2 patients, WBRT in 2, GKR in 1 and operation in 1. The median intracranial PFS and OS after intracranial metastasis was 5.2 (±0.42) and 6.8 (±0.38) months.

CONCLUSIONS

Cyst aspiration and GKR were feasible and safe but not very efficient, which could be an alternative option for large cystic metastases in patients who could not expect longer survival time.

Predictors of individual tumor local control after stereotactic radiosurgery for non-small cell lung cancer brain metastases

PURPOSE

To evaluate local control rates and predictors of individual tumor local control for brain metastases from non-small cell lung cancer (NSCLC) treated with stereotactic radiosurgery (SRS).

METHODS AND MATERIALS

Between June 1998 and May 2011, 401 brain metastases in 228 patients were treated with Gamma Knife single-fraction SRS. Local failure was defined as an increase in lesion size after SRS. Local control was estimated using the Kaplan-Meier method. The Cox proportional hazards model was used for univariate and multivariate analysis. Receiver operating characteristic analysis was used to identify an optimal cutpoint for conformality index relative to local control. A P value <.05 was considered statistically significant.

RESULTS

Median age was 60 years (range, 27-84 years). There were 66 cerebellar metastases (16%) and 335 supratentorial metastases (84%). The median prescription dose was 20 Gy (range, 14-24 Gy). Median overall survival from time of SRS was 12.1 months. The estimated local control at 12 months was 74%. On multivariate analysis, cerebellar location (hazard ratio [HR] 1.94, P=.009), larger tumor volume (HR 1.09, P<.001), and lower conformality (HR 0.700, P=.044) were significant independent predictors of local failure. Conformality index cutpoints of 1.4-1.9 were predictive of local control, whereas a cutpoint of 1.75 was the most predictive (P=.001). The adjusted Kaplan-Meier 1-year local control for conformality index ≥ 1.75 was 84% versus 69% for conformality index <1.75, controlling for tumor volume and location. The 1-year adjusted local control for cerebellar lesions was 60%, compared with 77% for supratentorial lesions, controlling for tumor volume and conformality index.

CONCLUSIONS

Cerebellar tumor location, lower conformality index, and larger tumor volume were significant independent predictors of local failure after SRS for brain metastases from NSCLC. These results warrant further investigation in a prospective setting.

Stereotactic radiosurgery (SRS) for brain metastases: a systematic review

In many patients with brain metastases, the primary therapeutic aim is symptom palliation and maintenance of neurologic function, but in a subgroup, long-term survival is possible. Local control in the brain, and absent or controlled extracranial sites of disease are prerequisites for favorable survival. Stereotactic radiosurgery (SRS) is a focal, highly precise treatment option with a long track record. Its clinical development and implementation by several pioneering institutions eventually rendered possible cooperative group randomized trials. A systematic review of those studies and other landmark studies was undertaken. Most clinicians are aware of the potential benefits of SRS such as a short treatment time, a high probability of treated-lesion control and, when adhering to typical dose/volume recommendations, a low normal tissue complication probability. However, SRS as sole first-line treatment carries a risk of failure in non-treated brain regions, which has resulted in controversy around when to add whole-brain radiotherapy (WBRT). SRS might also be prescribed as salvage treatment in patients relapsing despite previous SRS and/or WBRT. An optimal balance between intracranial control and side effects requires continued research efforts.

Treatment of single or multiple brain metastases by hypofractionated stereotactic radiotherapy using helical tomotherapy

This study investigated the clinical outcomes of a 4-fraction stereotactic radiotherapy (SRT) study using helical tomotherapy for brain metastases. Between August 2009 and June 2013, 54 patients with a total of 128 brain metastases underwent SRT using tomotherapy. A total dose of 28 or 28.8 Gy at 80% isodose was administered in 4 fractions for all tumors. The mean gross tumor volume (GTV) was 1.9 cc. Local control (LC) rates at 6, 12, and 18 months were 96%, 91%, and 88%, respectively. The 12-month LC rates for tumors with GTV ≤0.25, >0.25 and ≤1, and >1 cc were 98%, 82%, and 93%, respectively; the rates were 92% for tumors >3 cc and 100% for >10 cc. The 6-month rates for freedom from distant brain failure were 57%, 71%, and 55% for patients with 1, 2, and >3 brain metastases, respectively. No differences were significant. No major complications were observed. The 4-fraction SRT protocol provided excellent tumor control with minimal toxicity. Distant brain failure was not so frequent, even in patients with multiple tumors. The results of the current study warrant a prospective randomized study comparing single-fraction stereotactic radiosurgery (SRS) with SRT in this patient population.

Local control and toxicity outcomes in brainstem metastases treated with single fraction radiosurgery: is there a volume threshold for toxicity?

Gamma Knife Radiosurgery (GKRS) has been reported in the treatment of brainstem metastases while dose volume toxicity thresholds remain mostly undefined. A retrospective review of 52 brainstem metastases in 44 patients treated with GKRS was completed. A median dose of 18 Gy (range 10-22 Gy) was prescribed to the tumor margin (median 50 % isodose). 25 patients had undergone previous whole brain radiation therapy. Toxicity was graded by the LENT-SOMA scale. Mean and median follow-up was 10 and 6 months. Only 3 of the 44 patients are living. Multiple brain metastases were treated in 75 % of patients. Median size of lesions was 0.134 cc, (range 0.013-6.600 cc). Overall survival rate at 1 year was 32 % (95 % CI 51.0-20.1 %) with a median survival time of 6 months (95 % CI 5.0-16.5). Local control rate at 6 months and 1 year was 88 % (95 % CI 70-95 %) and 74 % (95 % CI 52-87 %). Cause of death was neurologic in 17 patients, non-neurologic in 20 patients, and unknown in four. Four patients experienced treatment related toxicities. Univariate analysis of tumor volume revealed that volume greater than 1.0 cc predicted for toxicity. A strategy of using lower marginal doses with GKRS to brain stem metastases appears to lead to a lower local control rate than seen with lesions treated within the standard dose range in other locations. Tumor size greater than 1.0 cc predicted for treatment-related toxicity.

Stereotactic radiotherapy for large solitary brain metastases

PURPOSE

To assess effectiveness and toxicity levels of stereotactic radiation therapy without whole brain radiation therapy in patients with solitary brain metastases larger than 3cm.

PATIENTS AND METHODS

Between June 2007 and March 2009, 12 patients received fractionated stereotactic radiation therapy and 24 patients underwent stereotactic radiosurgery. For the fractionated stereotactic radiation therapy group, 3×7.7Gy were delivered to the planning target volume (PTV); median volume and diameter were 29.4 cm(3) and 4.4cm, respectively. For the stereotactic radiosurgery group, 14Gy were delivered to the PTV; median volume and diameter were 15.6 cm(3) and 3.7cm, respectively.

RESULTS

Median follow-up was 218 days. For the fractionated stereotactic radiation therapy group, local control rates were 100% at 360 days and 64% at 720 days; for the stereotactic radiosurgery group, rates were 58% at 360 days and 48% at 720 days (P=0.06). Median survival time was 504 days for the fractionated stereotactic radiation therapy group and 164 days for the stereotactic radiosurgery group (P=0.049). Two cases of grade 2 toxicity were observed in the fractionated stereotactic radiation therapy group, and 6 cases of grade 1-2 toxicity, in the stereotactic radiosurgery group.

CONCLUSIONS

This study provides data to support that fractionated stereotactic radiation therapy without whole brain radiation therapy with a margin dose of 3 fractions of 7.7Gy for treatment of solitary large brain metastases is efficient and well-tolerated. Because of the significant improvement in overall survival, this schedule should be assessed in a randomized trial.

Special treatment issues in non-small cell lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines

BACKGROUND

This guideline updates the second edition and addresses patients with particular forms of non-small cell lung cancer that require special considerations, including Pancoast tumors, T4 N0,1 M0 tumors, additional nodules in the same lobe (T3), ipsilateral different lobe (T4) or contralateral lung (M1a), synchronous and metachronous second primary lung cancers, solitary brain and adrenal metastases, and chest wall involvement.

METHODS

The nature of these special clinical cases is such that in most cases, meta-analyses or large prospective studies of patients are not available. To ensure that these guidelines were supported by the most current data available, publications appropriate to the topics covered in this article were obtained by performing a literature search of the MEDLINE computerized database. Where possible, we also reference other consensus opinion statements. Recommendations were developed by the writing committee, graded by a standardized method, and reviewed by all members of the Lung Cancer Guidelines panel prior to approval by the Thoracic Oncology NetWork, Guidelines Oversight Committee, and the Board of Regents of the American College of Chest Physicians.

RESULTS

In patients with a Pancoast tumor, a multimodality approach appears to be optimal, involving chemoradiotherapy and surgical resection, provided that appropriate staging has been carried out. Carefully selected patients with central T4 tumors that do not have mediastinal node involvement are uncommon, but surgical resection appears to be beneficial as part of their treatment rather than definitive chemoradiotherapy alone. Patients with lung cancer and an additional malignant nodule are difficult to categorize, and the current stage classification rules are ambiguous. Such patients should be evaluated by an experienced multidisciplinary team to determine whether the additional lesion represents a second primary lung cancer or an additional tumor nodule corresponding to the dominant cancer. Highly selected patients with a solitary focus of metastatic disease in the brain or adrenal gland appear to benefit from resection or stereotactic radiosurgery. This is particularly true in patients with a long disease-free interval. Finally, in patients with chest wall involvement, provided that the tumor can be completely resected and N2 nodal disease is absent, primary surgical resection should be considered.

CONCLUSIONS

Carefully selected patients with more uncommon presentations of lung cancer may benefit from an aggressive surgical approach.

Stereotactic radiosurgery in the treatment of brain metastases: the current evidence

Chemotherapy has made substantial progress in the therapy of systemic cancer, but the pharmacological efficacy is insufficient in the treatment of brain metastases. Fractionated whole brain radiotherapy (WBRT) has been a standard treatment of brain metastases, but provides limited local tumor control and often unsatisfactory clinical results. Stereotactic radiosurgery using Gamma Knife, Linac or Cyberknife has overcome several of these limitations, which has influenced recent treatment recommendations. This present review summarizes the current literature of single session radiosurgery concerning survival and quality of life, specific responses, tumor volumes and numbers, about potential treatment combinations and radioresistant metastases. Gamma Knife and Linac based radiosurgery provide consistent results with a reproducible local tumor control in both single and multiple brain metastases. Ideally minimum doses of ≥18Gy are applied. Reported local control rates were 90-94% for breast cancer metastases and 81-98% for brain metastases of lung cancer. Local tumor control rates after radiosurgery of otherwise radioresistant brain metastases were 73-90% for melanoma and 83-96% for renal cell cancer. Currently, there is a tendency to treat a larger number of brain metastases in a single radiosurgical session, since numerous studies document high local tumor control after radiosurgical treatment of >3 brain metastases. New remote brain metastases are reported in 33-42% after WBRT and in 39-52% after radiosurgery, but while WBRT is generally applied only once, radiosurgery can be used repeatedly for remote recurrences or new metastases after WBRT. Larger metastases (>8-10cc) should be removed surgically, but for smaller metastases Gamma Knife radiosurgery appears to be equally effective as surgical tumor resection (level I evidence). Radiosurgery avoids the impairments in cognition and quality of life that can be a consequence of WBRT (level I evidence). High local efficacy, preservation of cerebral functions, short hospitalization and the option to continue a systemic chemotherapy are factors in favor of a minimally invasive approach with stereotactic radiosurgery.

Recursive partitioning analysis for the prediction of stereotactic radiosurgery brain metastases lesion control

PURPOSE

The objective of this investigation was to identify independent pretreatment factors that predict for control of local brain metastases (BM) in a large single-institution series of patients receiving stereotactic radiosurgery (SRS). Recursive partitioning analysis was used to potentially identify a class of patients with durable lesion control characteristics.

METHODS

A retrospective SRS database containing baseline characteristics, treatment details, and follow-up data of newly diagnosed patients with 1-3 BM (on magnetic resonance imaging) treated with linear accelerator-based SRS was created. Three study endpoints were used: time to progression (primary endpoint, individual lesion progression; n = 536), time to first progression (secondary endpoint, first lesion progression on an individual patient basis; n = 380), and overall survival (secondary endpoint; n = 380). Recursive partitioning analysis (RPA) was performed to identify predictors of time to progression.

RESULTS

Multivariable analysis demonstrated that lesion aspect/phenotype and radiotherapy schedule were independent factors associated with both progression outcomes. Presence of tumor necrosis was found to be associated with a significant hazard of progression (hazard ratio >3), whereas use of the most intense radiotherapy fractionation schedule (21 Gy in one fraction) was associated with significant reductions in progression (hazard ratio <0.3). RPA using SRS dose and lesion aspect/phenotype was created and described three distinct prognostic groups.

CONCLUSIONS

RPA of a large retrospective database of patients receiving SRS confirmed previous observations regarding the importance of SRS dose and lesion aspect/phenotype in lesion control and overall survival. The SRS lesion analysis may help to stratify future clinical trials and better define patient care options and prognosis.

Prognostic factors for patients in postoperative brain metastases from surgically resected non-small cell lung cancer

BACKGROUND

Postoperative recurrence in non-small cell lung cancer (NSCLC) reduces the life expectancy of patients. In this retrospective study, we investigated the prognostic factors in patients with postoperative brain metastases from surgical resected non-small cell lung cancer (NSCLC).

METHODS

We conducted a retrospective chart review of patients who had undergone resection for NSCLC between April 2004 and February 2009 and found 65 had experienced postoperative brain metastases by March 2010. We reviewed these patients for clinicopathological information, treatments and responses to treatment, and overall survival.

RESULTS

The 5-year survival rate after the diagnosis of brain metastases was 15.4 %. Significantly favorable prognostic factors for patients after a diagnosis of brain metastases included female gender, adenocarcinoma, a small number (1-3) of brain metastases, no extracranial metastasis at the diagnosis of brain metastases, radiation treatment (whole-brain radiation and/or stereotactic irradiation), and local treatment [stereotactic irradiation and/or surgical operation (craniotomy)]. Furthermore, in patients with only brain metastases as the postoperative initial recurrence, the favorable positive prognostic factors included a small number (1-3) of brain metastases, adjuvant chemotherapy, chemotherapy (including adjuvant and other chemotherapy and excluding epidermal growth factor receptor-tyrosine kinase inhibitors), and local treatment.

CONCLUSIONS

Our study found that the foregoing clinical characteristics in postoperative brain metastases and the administration of treatment contributed to patient life expectancy.

Accelerator-based stereotactic radiosurgery for brainstem metastases

BACKGROUND

Stereotactic radiosurgery represents a noninvasive alternative treatment for intracranial metastases.

OBJECTIVE

To investigate the treatment outcome of linear accelerator-based stereotactic radiosurgery (linac-SRS) for brainstem metastases.

METHODS

We retrospectively reviewed our database of patients who were diagnosed with brainstem metastases and underwent linac-SRS between 1997 and 2008 at the University of California, Los Angeles.

RESULTS

A total of 45 patients with 48 brainstem metastases were treated. The median target volume was 0.40 mL (range, 0.02-5.70 mL), and median prescription dose was 14 Gy (range, 10-17 Gy) at 90% isodose curve. The median survival time was 11.6 months. Longer survival time was associated with higher Karnofsky performance status. The local control rate was 92% at 6 months and 88% at 1 year. Univariate analysis demonstrated a significant relationship between local control and tumor volume (≤0.4 mL vs >0.4 mL, P = .023) and SRS mode (conventional circular arc vs dynamic conformal arc, P = .044). There was a trend toward improved local control and prescription dose >14 Gy (P = .059). Two patients had brainstem complications following treatment, and the complication rate was 4.7% at 2 years. Serious morbidity occurred with 17 Gy.

CONCLUSION

Linac-SRS using a median dose of 14 Gy provided excellent local control in patients with brainstem metastases less than 0.4 mL with relatively low serious morbidity. The results of the study support the use of linac-SRS for patients with brainstem metastases. We advocate 14 to 16 Gy, given the high local control rate and low complication rate with this dose.

Hypofractionated stereotactic radiotherapy of limited brain metastases: a single-centre individualized treatment approach

Background

We retrospectively report treatment results of our single-centre experience with hypofractionated stereotactic radiotherapy (hfSRT) of limited brain metastases in primary and recurrence disease situations. Our aim was to find the most effective and safe dose concept.

Methods

From 04/2006 to 12/2010, 75 patients, with 108 intracranial metastases, were treated with hfSRT. 52 newly diagnosed metastases (48%), without up-front whole brain radiotherapy (WBRT), received hfSRT as a primary treatment. 56 metastases (52%) received a prior WBRT and were treated in this study in a recurrence situation. Main fractionation concepts used for primary hfSRT were 6-7x5 Gy (61.5%) and 5x6 Gy (19.2%), for recurrent hfSRT 7-10x4 Gy (33.9%) and 5-6x5 Gy (33.9%).

Results

Median overall survival (OS) of all patients summed up to 9.1 months, actuarial 6-and 12-month-OS was 59% and 35%, respectively. Median local brain control (LC) was 11.9 months, median distant brain control (DC) 3.9 months and intracranial control (IC) 3.4 months, respectively. Variables with significant influence on OS were Gross Tumour Volume (GTV) (p = 0.019), the biological eqivalent dose (calculated on a 2 Gy single dose, EQD2, α/β = 10) < and ≥ median of 39 Gy (p = 0.012), extracerebral activity of the primary tumour (p < 0.001) and the steroid uptake during hfSRT (p = 0.03). LC was significantly influenced by the EQD2, ≤ and > 35 Gy (p = 0.004) in both uni- and multivariate Cox regression analysis. Median LC was 14.9 months for EQD2 >35 Gy and 3.4 months for doses ≤35 Gy, respectively. Early treatment related side effects were usually mild. Nevertheless, patients with a EQD2 >35 Gy had higher rates of toxicity (31%) than ≤35 Gy (8.3%, p=0.026).

Conclusion

Comparing different dose concepts in hfSRT, a cumulative EQD2 of ≥35 Gy seems to be the most effective concept in patients with primary or recurrent limited brain metastases. Despite higher rates of only mild toxicity, this concept represents a safe treatment option.

Brain metastases research 1990-2010: pattern of citation and systematic review of highly cited articles

BACKGROUND

High and continuously increasing research activity related to different aspects of prevention, prediction, diagnosis and treatment of brain metastases has been performed between 1990 and 2010. One of the major databases contains 2695 scientific articles that were published during this time period. Different measures of impact, visibility, and quality of published research are available, each with its own pros and cons. For this overview, article citation rate was chosen.

RESULTS

Among the 10 most cited articles, 7 reported on randomized clinical trials. Nine covered surgical or radiosurgical approaches and the remaining one a widely adopted prognostic score. Overall, 30 randomized clinical trials were published between 1990 and 2010, including those with phase II design and excluding duplicate publications, for example, after longer followup or with focus on secondary endpoints. Twenty of these randomized clinical trials were published before 2008. Their median number of citations was 110, range 13-1013, compared to 5-6 citations for all types of publications. Annual citation rate appeared to gradually increase during the first 2-3 years after publication before reaching high levels.

CONCLUSIONS

A large variety of preclinical and clinical topics achieved high numbers of citations. However, areas such as quality of life, side effects, and end-of-life care were underrepresented. Efforts to increase their visibility might be warranted.