Gamma Knife Radiosurgery in the management of single and multiple brain metastases

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.

Development of a 3D printed phantom for commissioning and quality assurance of multiple brain targets stereotactic radiosurgery

Single plan techniques for multiple brain targets (MBT) stereotactic radiosurgery (SRS) are now routine. Patient specific quality assurance (QA) for MBT poses challenges due to the limited capabilities of existing QA tools which necessitates several plan redeliveries. This study sought to develop an SRS QA phantom that enables flexible MBT patient specific QA in a single delivery, along with complex SRS commissioning. PLA marble and PLA StoneFil materials were selected based on the literature and previous research conducted in our department. The HU numbers were investigated to determine the appropriate percentage infill for skull and soft-tissue equivalence. A Prusa MK3S printer in conjunction with the above-mentioned filaments were used to print the SRS QA phantom. Quality control (QC) was performed on the printed skull, film inserts and plugs for point dose measurements. EBT3 film and point dose measurements were performed using a CC04 ionisation chamber. QC demonstrated that the SRS QA phantom transverse, coronal and sagittal film planes were orthogonal within 0.5°. HU numbers for the skull, film inserts and plugs were 858 ± 20 and 35 ± 12 respectively. Point and EBT3 film dose measurements were within 2.5% and 3%/2 mm 95% gamma pass rate, respectively except one Gross Tumour Volume (GTV) that had a slightly lower gamma pass rate. Dose distributions to five GTVs were measured with EBT3 film in a single plan delivery on CyberKnife. In conclusion, an SRS QA phantom was designed, and 3D printed and its use for performing complex MBT patient specific QA in a single delivery was demonstrated.

Predicting long‑term survival following involved site radiotherapy for oligometastases

The majority of cancer-associated mortalities are due to distant metastases, and systemic therapy alone is generally not curative. Patients with oligometastases are amenable to involved site radiotherapy with the possibility of long-term disease-free survival; however, prognostic factors remain poorly defined. The present retrospective, single institution study consisted of consecutive adult patients with oligometastases from solid tumor malignancy referred to a single high volume radiation oncologist between January 2014 and December 2021. Oligometastases were defined as ≤5 extracranial or intracranial metastatic lesions where all sites of active disease are treatable, including patients requiring treatment of the primary tumor and/or regional lymph nodes. The study population consisted of 130 patients with 207 treated distant metastases. Radical radiotherapy was administered to all areas of known residual disease and included stereotactic radiotherapy (median dose, 27 Gy in 3 fractions) or intensity modulated radiotherapy (median dose, 50 Gy in 15 fractions). At a median follow-up of 28.8 months, the median overall survival was 37.9 months with a 4-year overall survival of 41.1%. The median progression-free survival was 12.3 months and the 4-year progression-free survival was 22.6%. On multivariate an1alysis, the strongest predictors of overall survival were age, ECOG performance status, primary prostate, breast or kidney tumor and pre-radiation serum albumin (P≤0.01 for all). Overall, the present study demonstrated that long-term overall survival was possible after radical treatment for oligometastases and identified potential prognostic factors.

Clinical and pathological factors and outcome of central nervous system metastasis in breast cancer

Background

In Switzerland, approximately 6000 new breast cancer cases and 1300 deaths are reported annually. Brain metastasis from breast cancer (BMBC) has a major effect on prognosis. This study aimed to identify prognostic factors for overall survival (OS) in a cohort of Swiss patients with BMBC. This study evaluated the prognosis on older BMBC, which has not been completely addressed in the literature.

Methods

We performed a retrospective chart review analysis with the primary endpoint of OS after a diagnosis of BMBC. The study population was divided into 2 groups based on an OS cut-off value of 12 months after diagnosis. Univariate and multivariate analyses of several risk factors, including age, were performed. To evaluate differences in OS according to age, we performed a secondary analysis to examine the prognostic value of clinical symptoms, metastatic pattern, and lymph node involvement in an older (≥65 years) vs. younger (<65 years) cohort.

Results

From 1989 to 2019, 55 patients were identified as having BMBC, among whom 47 patients were confirmed to be dead. The median patient age was 58 years (range 25-83 years). Comorbidities were present in 45 (81.8%) patients. The median survival in the OS <12 and OS ≥12 months groups was 4.3 and 30.7 months, respectively (p<0.001). Multivariate analysis revealed no significant differences in terms of comorbidities, medication use, M-stage, and symptomatology between the 2 groups. Additionally, there was no significant difference in OS in the 2 subgroups of patients aged <65 and ≥65 years.

Discussion

We concluded that age should not be a decisive factor in therapy planning for advanced breast cancer patients with BMBC.

Dosimetric Parameters in Hypofractionated Stereotactic Radiotherapy for Brain Metastases: Do Flattening Filter-Free Beams Bring Benefits? A Preliminary Study

PURPOSE

This study aimed to compare the dosimetric results of flattening filter-free (FFF) vs. flattened (FF) treatment plans for fractionated stereotactic radiotherapy (fSRT), with the goal to highlight potential advantages of FFF beams.

METHODS

A group of 18 patients with brain metastases treated with fSRT (30 Gy delivered in 5 fractions) were included. The dosimetric parameters evaluated were: (1) physical dosimetric parameters (number of monitor units (MUs), conformity index (CI), dose gradient index (DGI), beam on time (BOT)); (2) clinical dosimetric parameters pertaining to target volume (PTV) and organs at risk (OARs). Two treatment plans were performed for all patients: one used 6 MV FFF beams and the other used 6 MV flattened beams.

RESULTS

A slight increase in MUs was observed for the FFF mode (+23.3 MUs). The CI showed a difference of -2.7% for the FF plans (p = 0.28), correlated with a poorer coverage of the PTV. DGI values reported in terms of PTV are in line with international recommendations and showed a +1.9% difference for FFF plans. An average BOT of 90.3 s was reported for FFF plans, which was 2.3 times shorter than that required for FF plans delivery (p ≤ 0.001). A slight decrease of PTV coverage (-1.26%, p = 0.036) for FF plans can be considered relevant, but no other significant differences were observed between the two optimizations. No statistically significant benefit of using FFF beams to reduce V₂₀ for normal brain could be demonstrated.

CONCLUSION

These dosimetric results encourage the implementation of fSRT with standard flattened beams in centers where FFF linacs are not available.

Analysis of Key Clinical Variables and Radiological Manifestations Associated with the Treatment Response of Patients with Brain Metastases to Stereotactic Radiosurgery

Background: Stereotactic radiosurgery (SRS) is considered a promising treatment for brain metastases (BM) with better healing efficacy, relatively faster treatment time, and lower neurotoxicity, which can achieve local control rates above 70%. Although SRS improves the local control of BM, this may not translate into improvements in survival time. Thus, screening out the key factors influencing the treatment response to SRS, instead of the survival time following SRS, might be of more significance. This may assist doctors when making adjustments to treatment strategies for patients with BM. Methods: This is a retrospective review of 696 patients with BM who were treated with SRS at Huashan Hospital, Fudan University between June 2015 and February 2020. According to the patients’ treatment response to SRS, the patients were divided into an improved group (IG) and a progressive group (PG). The clinical data and magnetic resonance imaging (MRI) performed pre- and post-treatment were collected for the two groups. Five clinical variables (gender, age, Karnofsky performance status (KPS), primary tumor type, and extracranial lesion control) and seven radiological manifestations (location, number, volume, maximum diameter, edema index (EI), diffusion weighted imaging (DWI) sequence signal, and enhanced pattern) were selected and compared. A stepwise regression analysis was performed in order to obtain the best prediction effect of a group of variables and their regression coefficients, and finally to build an SRS treatment response scoring model based on the coefficients. The performance of the model was evaluated by calculating the AUC and performing the Hosmer–Lemeshow test. Results: A total of 323 patients were enrolled in the study based on the inclusion and exclusion criteria, including 209 patients in the IG and 114 patients in the PG. In the Chi-square test and t-test analysis, the significant p values of KPS, extracranial lesion control, volume, and EI were less than 0.05. Moreover, the cut-off values for volume and EI were 1801.145 mm3 and 3.835, respectively. The scoring model that was based on multivariate logistic regression coefficients performed better, achieving AUCs of 0.755 ± 0.062 and 0.780 ± 0.061 for the internal validation and validation cohorts, with p values of 0.168 and 0.073 for the Hosmer–Lemeshow test. Conclusions: KPS, extracranial lesion control, tumor volume, and EI had a certain correlation with the treatment response to SRS. Scoring models that are based on these variables can accurately predict the treatment response of patients with BM to SRS, thereby assisting doctors to make an appropriate first treatment strategy for patients with BM to a certain degree.

Radiosurgery for Five to Fifteen Brain Metastases: A Single Centre Experience and a Review of the Literature

Purpose

Stereotactic radiosurgery (SRS) is now mainstream for patients with 1-4 brain metastases however the management of patients with 5 or more brain metastases remains controversial. Our aim was to evaluate the clinical outcomes of patients with 5 or more brain metastases and to compare with published series as a benchmarking exercise.

Methods

Patients with 5 or more brain metastases treated with a single isocentre dynamic conformal arc technique on a radiosurgery linac were identified from the institutional database. Endpoints were local control, distant brain failure, leptomeningeal disease and overall survival. Dosimetric data were extracted from the radiosurgery plans. Series reporting outcomes following SRS for multiple brain metastases were identified by a literature search.

Results

36 patients, of whom 35 could be evaluated, received SRS for 5 or more brain metastases between February 2015 and October 2021. 25 patients had 5-9 brain metastases (group 1) and 10 patients had 10-15 brain metastases (group 2). The mean number of brain metastases in group 1 was 6.3 (5-9) and 12.3 (10-15) in group 2. The median cumulative irradiated volume was 4.6 cm³ (1.25-11.01) in group 1 and 7.2 cm³ (2.6-11.1) in group 2. Median follow-up was 12 months. At last follow-up, local control rates per BM were 100% and 99.8% as compared with a median of 87% at 1 year in published series. Distant brain failure was 36% and 50% at a median interval of 5.2 months and 7.4 months after SRS in groups 1 and 2 respectively and brain metastasis velocity at 1 year was similar in both groups (9.7 and 11). 8/25 patients received further SRS and 7/35 patients received whole brain radiotherapy. Median overall survival was 10 months in group 1 and 15.7 months in group 2, which compares well with the 7.5 months derived from the literature. There was one neurological death in group 2, leptomeningeal disease was rare (2/35) and there were no cases of radionecrosis.

Conclusion

With careful patient selection, overall survival following SRS for multiple brain metastases is determined by the course of the extracranial disease. SRS is an efficacious and safe modality that can achieve intracranial disease control and should be offered to patients with 5 or more brain metastases and a constellation of good prognostic factors.

The role of stereotactic radiotherapy in addition to immunotherapy in the management of melanoma brain metastases: results of a systematic review

Aim of this study was to systematically review the literature to assess efficacy and safety of stereotactic radiotherapy (SRT) in combination with immunotherapy for the treatment of melanoma brain metastases (MBM). The literature was searched using PubMed, Scopus, and Embase. Studies comparing SRT plus immunotherapy versus SRT or immunotherapy alone were deemed eligible for inclusion. Two studies showed improved overall survival after SRT plus immunotherapy in melanoma cancer patients with brain metastases. Three studies reported data on LC and DFS showing as SRT plus immunotherapy did not improve local control and DFS rates. G3-G4 toxicity was reported in only one study (20% in the SRT plus immunotherapy group versus 23% in the immunotherapy group). Despite SRT plus concurrent immunotherapy seems associated with possible survival advantage and low ≥ G3 late toxicity rates, the quality of evidence is very low. Therefore, in patients with brain metastases from melanoma, SRT plus immunotherapy should be evaluated on an individual basis after discussion by a multidisciplinary team.

Single-fraction versus hypofractionated gamma knife radiosurgery for small metastatic brain tumors

Stereotactic radiosurgery (SRS) has become a standard of care for the treatment of metastatic brain tumors (METs). Although a better balance of tumor control and toxicity of hypofractionated SRS (hfSRS) compared with single-fraction SRS (sfSRS) was demonstrated in large METs, there is no data comparing two approaches for small METs (< 4 cm³). It was aimed to compare clinical outcomes between sfSRS versus hfSRS Gamma Knife radiosurgery (GKRS) in a series of patients with unresected, small METs. Patients (n = 208) treated with sfGKRS or hfGKRS between June 2017 and May 2020 were retrospectively examined in a single center. The co-primary endpoints of local control (LC) and toxicity were estimated by applying the Kaplan-Meier method. Multivariate analysis using Cox proportional hazards (HR) modeling was used to assess the effect of independent variables on the outcomes. The actuarial LC rate was 99.7% at six months and 98.8% at 18 months in the sfGKRS group, and 99.4% and 94.3% in the hfGKRS group (p = 0.089), respectively. In multivariate analysis, MET volume (p = 0.023, HR 2.064) and biologically effective dose (BED₁₀) (p < 0.0001, HR 0.753) was associated with LC. In total, treatment-related toxicity was observed in 13 (8.7%) patients during a median period of 10 weeks (range 1-31). Radiation necrosis was observed in four patients (1.9%), and all patients were in the sfGKRS group (p = 0.042). Only the maximum dose was associated with toxicity (p = 0.032, HR 1.047). Our current results suggest that hfGKRS is advantageous and beneficial also in patients with unresected, small METs.

Radiographic Trends for Infield Recurrence After Radiosurgery for Cerebral Metastases

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

A Simple and Practical Scoring System for Radiosurgical Treatment in Patients with Brain Metastases

BACKGROUND

The study aimed to investigate the prognostic factors for patients with brain metastases undergoing radiosurgical treatment and to introduce a simple and practical scoring system for the prediction of survival time.

METHODS

We retrospectively analyzed data for 311 patients treated with Gamma Knife radiosurgery at a single institute. The mean age at time of treatment was 60 years (range 23-86 years), and the median Karnofsky performance status (KPS) score was 90 (range 60-100). Using a new prognostic index, the prognostic index for brain metastases (PIBM), the patients were categorized into 3 groups according to the primary tumor status and KPS score. We performed survival analysis and compared the prognostic ability of the PIBM with other published indices.

RESULTS

During the median follow-up duration of 8.2 months (range 0.1-109 months), the median overall survival time was 9.1 months. Stable primary tumor status (hazard ratio [HR] 0.497, 95% confidence interval [CI] 0.321-0.769, p = 0.002) and KPS score ≥90 (HR 1.407, 95% CI 1.018-1.946, p = 0.039) significantly predicted longer overall survival. The PIBM showed the lowest Akaike information criterion value and the highest integrated area under the curve value compared with other prognostic indices.

CONCLUSIONS

The PIBM may be a more accurate prognostic indicator than other published indices. Although this new and practical prognostic index requires further validation in larger cohort studies, we suggest that the PIBM could be useful to predict survival time and inform appropriate management of patients with brain metastases.

Deep-Learning Detection of Cancer Metastases to the Brain on MRI

BACKGROUND

Approximately one-fourth of all cancer metastases are found in the brain. MRI is the primary technique for detection of brain metastasis, planning of radiotherapy, and the monitoring of treatment response. Progress in tumor treatment now requires detection of new or growing metastases at the small subcentimeter size, when these therapies are most effective.

PURPOSE

To develop a deep-learning-based approach for finding brain metastasis on MRI.

STUDY TYPE

Retrospective.

SEQUENCE

Axial postcontrast 3D T₁ -weighted imaging.

FIELD STRENGTH

1.5T and 3T.

POPULATION

A total of 361 scans of 121 patients were used to train and test the Faster region-based convolutional neural network (Faster R-CNN): 1565 lesions in 270 scans of 73 patients for training; 488 lesions in 91 scans of 48 patients for testing. From the 48 outputs of Faster R-CNN, 212 lesions in 46 scans of 18 patients were used for training the RUSBoost algorithm (MatLab) and 276 lesions in 45 scans of 30 patients for testing.

ASSESSMENT

Two radiologists diagnosed and supervised annotation of metastases on brain MRI as ground truth. This data were used to produce a 2-step pipeline consisting of a Faster R-CNN for detecting abnormal hyperintensity that may represent brain metastasis and a RUSBoost classifier to reduce the number of false-positive foci detected.

STATISTICAL TESTS

The performance of the algorithm was evaluated by using sensitivity, false-positive rate, and receiver's operating characteristic (ROC) curves. The detection performance was assessed both per-metastases and per-slice.

RESULTS

Testing on held-out brain MRI data demonstrated 96% sensitivity and 20 false-positive metastases per scan. The results showed an 87.1% sensitivity and 0.24 false-positive metastases per slice. The area under the ROC curve was 0.79.

CONCLUSION

Our results showed that deep-learning-based computer-aided detection (CAD) had the potential of detecting brain metastases with high sensitivity and reasonable specificity.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY STAGE: 2 J. Magn. Reson. Imaging 2020;52:1227-1236.

Postoperative radiosurgery for the treatment of metastatic brain tumor: Evaluation of local failure and leptomeningeal disease

In patients undergoing surgical resection of a metastatic brain tumor, whole brain radiation therapy reduces the risk of recurrence and neurologic death. Focal radiation has the potential to mitigate neurocognitive side effects. We present an institutional experience of postoperative radiosurgery for the treatment of brain metastases. A retrospective review of a prospectively maintained institutional radiosurgery database was performed for the years 2005-2015 identifying all adult patients treated with postoperative radiosurgery to the tumor bed. Primary endpoints include local recurrence and postoperative LMD. Kaplan-Meier curves and Cox regression were used to evaluate time to local recurrence and postoperative LMD. Ninety-one patients received adjuvant focal radiation for a brain metastasis. Median radiographic follow-up among patients who had not developed a local failure was 9 months. Of the 91 patients, 20 (22%) developed local recurrence and 32 (35%) experienced postoperative LMD. Freedom from local recurrence and LMD at 1 year was 84% and 69%, respectively. In multivariable models, predictors of local failure included the presence of more than one brain metastasis (HR = 2.65, p = .04) with a preoperative tumor diameter of >3 cm (HR = 4.16, p = .06) trending toward significance. There was a trend to a higher risk of LMD with >1 tumor (HR 2.07, p = .06) and breast cancer (HR 2.37, p = .07). More than one metastasis is an independent predictor of local and leptomeningeal failure following postoperative radiosurgery. The high rate of LMD was likely related to the liberal definition of LMD to include focal dural recurrences.

Successful gamma knife radiosurgery combined with S-1 in an elderly man with local recurrent pancreatic cancer: A case report

RATIONALE

Pancreatic cancer is common in people older than 40 years, and the incidence peaks at the age of 70 years and older. Chemoradiotherapy has been generally considered a high-risk procedure in elderly patients with local recurrent pancreatic cancer. Gamma knife stereotactic radiosurgery has the advantage in protecting the surrounding tissues, and providing short-term effects. It has been successfully used in patients with brain metastases.The efficacy of GKSRS in other malignancies has barely been studied.S-1 is one of the key drug against metastatic and local advanced pancreatic cancer. The combination of GKSRS and S-1 in local recurrent pancreatic cancer has hardly been reported.

PATIENT CONCERNS

We present a rare case of a 76-year-old man with pancreatic cancer. He complained of recurrent abdominal pain and chronic pain in the right shoulder for more than 3 years.

DIAGNOSES

After several examinations, the diagnosis was carcinoma of the pancreas.

INTERVENTIONS

A resection of the pancreatic neoplasm was performed on June 21, 2011; he did not receive adjuvant chemotherapy. In April 2014, postoperative recurrence was confirmed in the head of the pancreas. The patient received gamma knife stereotactic radiosurgery (GKSRS) combined with S-1 treatment.

OUTCOMES

The patient showed complete response after 2 months. He has achieved an overall survival of 76 months with a very good performance status.

LESSONS

GKSRS applied to other malignancies has rarely been reported. S-1 is the key drug for adjuvant chemotherapy in resected pancreatic cancer. There are a few studies on this combination in local recurrent pancreatic cancer. GKSRS combined with S-1 seems to be a good option in improving efficacy and prolonging life in elderly patients with locally recurrent pancreatic cancer.

First follow-up radiographic response is one of the predictors of local tumor progression and radiation necrosis after stereotactic radiosurgery for brain metastases

Local progression (LP) and radiation necrosis (RN) occur in >20% of cases following stereotactic radiosurgery (SRS) for brain metastases (BM). Expected outcomes following SRS for BM include tumor control/shrinkage, local progression and radiation necrosis. 1427 patients with 4283 BM lesions were treated using SRS at Cleveland Clinic from 2000 to 2012. Clinical, imaging and radiosurgery data were collected from the database. Local tumor progression and RN were the primary end points and correlated with patient and tumor‐related variables. 5.7% of lesions developed radiographic RN and 3.6% showed local progression at 6 months. Absence of new extracranial metastasis (P < 0.001), response to SRS at first follow‐up scan (local progression versus stable size (P < 0.001), partial resolution versus complete resolution at first follow up [P = 0.009]), prior SRS to the same lesion (P < 0.001), IDL% (≤55; P < 0.001), maximum tumor diameter (>0.9 cm; P < 0.001) and MD/PD gradient index (≤1.8, P < 0.001) were independent predictors of high risk of local tumor progression. Absence of systemic metastases (P = 0.029), good neurological function at 1st follow‐up (P ≤ 0.001), no prior SRS to other lesion (P = 0.024), low conformity index (≤1.9) (P = 0.009), large maximum target diameter (>0.9 cm) (P = 0.003) and response to SRS (tumor progression vs. stable size following SRS [P < 0.001]) were independent predictors of high risk of radiographic RN. Complete tumor response at first follow‐up, maximum tumor diameter <0.9 cm, tumor volume <2.4 cc and no prior SRS to the index lesion are good prognostic factors with reduced risk of LP following SRS. Complete tumor response to SRS, poor neurological function at first follow‐up, prior SRS to other lesions and high conformity index are favorable factors for not developing RN. Stable or partial response at first follow‐up after SRS have same impact on local progression and RN compared to those with complete resolution or progression.

Cumulative Intracranial Tumor Volume and Number of Brain Metastasis as Predictors of Developing New Lesions After Stereotactic Radiosurgery for Brain Metastasis

OBJECTIVES

To identify risk factors associated with early distant radiographic progression in patients undergoing stereotactic radiosurgery (SRS) for brain metastases (BM).

METHODS

Following Institutional Review Board approval, data of 1427 patients (4283 BM lesions) who were treated by SRS at the Cleveland Clinic for 2000-2012 were collected. Local tumor progression (LTP), distant tumor progression (DTP), and radiographic radiation necrosis (RN) were the primary endpoints. Patient, imaging, radiosurgery, and tumor variables and follow-up data were collected.

RESULTS

The median number of targets was 2 (range, 1-17); 45% of the patients had a single lesion. DTP was observed in 10% at 3 months and 19% at 6 months. Patients with 5-10 target lesions for SRS were more likely to develop new lesions at both 3 and 6 months compared to those with 2-4 lesions (odds ratio [OR], 0.83, 95% confidence interval [CI], 0.40-0.85 and OR, 0.85, 95% CI, 0.45-0.86 respectively; P < 0.05). Younger age (<65 years; P < 0.001), higher number of lesions (>1; P < 0.001), cumulative intracranial tumor volume (CITV) <2.75 cc (P = 0.023), type of SRS (upfront and salvage vs. boost; P < 0.001), and tumor pathology (radiosensitive; P < 0.001), were independent predictors of early distant tumor progression following SRS.

CONCLUSIONS

The number of target lesions and low CITV are both independent predictors of early DTP following SRS for BM. Radiosensitive tumor histology, younger age (<65 years), and SRS without previous whole-brain radiation therapy (upfront or salvage) were also predictors of early DTP.

Validation of the graded prognostic assessment for lung cancer with brain metastases using molecular markers (lung-molGPA)

Background

Many patients with brain metastases from non-small cell lung cancer have limited survival, while others survive for several years, depending on patterns of spread, EGFR and ALK alterations, among others. The purpose of this study was to validate a new prognostic model (Lung-molGPA) originally derived from a North American database.

Patients and methods

This retrospective study included 269 German and Norwegian patients treated with individualized approaches, always including brain radiotherapy. Information about age, extracranial spread, number of brain metastases, performance status, histology, EGFR and ALK alterations was collected. The Lung-molGPA score was calculated as described by Sperduto et al.

Results

Median survival was 5.4 months. The score predicted survival in patients with adenocarcinoma histology and those with other types. For example, median survival was 3.0, 6.2, 14.7 and 25.0 months in the 4 different prognostic strata for adenocarcinoma. The corresponding figures were 2.4, 5.5 and 12.5 months in the 3 different prognostic strata for non-adenocarcinoma.

Conclusions

These results confirm the validity of the Lung-molGPA in an independent dataset from a different geographical region. However, median survival was shorter in 6 of 7 prognostic strata. Potential explanations include lead time bias and differences in treatment selection, both brain metastases-directed and systemically.

The TNM 8 M1b and M1c classification for non-small cell lung cancer in a cohort of patients with brain metastases

BACKGROUND AND PURPOSE

According to the recent TNM 8 classification, patients with metastatic non-small cell lung cancer (NSCLC) and single extrathoracic metastasis should be classified as stage M1b, while those with 2 or more metastases comprise stage M1c. The purpose of this study was to analyze the impact of this classification in patients with brain metastases.

MATERIALS AND METHODS

This retrospective study included 172 patients treated with individualized approaches. Actuarial survival was calculated. Uni- and multivariate analyses were performed.

RESULTS

Thirty patients (17%) were staged as M1b. Those with squamous cell cancer were more likely to harbor M1b disease (29%, adenocarcinoma 14%, other histology 17%, p = 0.16). Median survival was 5.4 months (8.0 months in case of M1b disease and 4.5 months in case of M1c disease, p = 0.001). Multivariate analysis confirmed the role of M1b stage. M1b patients managed with upfront surgery or radiosurgery had significantly longer median survival than those who received whole-brain irradiation (21.0 vs. 3.5 months, p = 0.0001) and the potential to survive beyond 5 years.

CONCLUSIONS

We found the M1b classification to provide clinically relevant information. The multivariate analysis suggested that patients with M1b disease, better performance status and younger age have better survival.

Repeat stereotactic radiosurgery as salvage therapy for locally recurrent brain metastases previously treated with radiosurgery

OBJECTIVE There are a variety of salvage options available for patients with brain metastases who experience local failure after stereotactic radiosurgery (SRS). These options include resection, whole-brain radiation therapy, laser thermoablation, and repeat SRS. There is little data on the safety and efficacy of repeat SRS following local failure of a prior radiosurgical procedure. This study evaluates the clinical outcomes and dosimetric characteristics of patients who experienced tumor recurrence and were subsequently treated with repeat SRS. METHODS Between 2002 and 2015, 32 patients were treated with repeat SRS for local recurrence of ≥ 1 brain metastasis following initial SRS treatment. The Kaplan-Meier method was used to estimate time-to-event outcomes including overall survival (OS), local failure, and radiation necrosis. Cox proportional hazards analysis was performed for predictor variables of interest for each outcome. Composite dose-volume histograms were constructed for each reirradiated lesion, and these were then used to develop a predictive dosimetric model for radiation necrosis. RESULTS Forty-six lesions in 32 patients were re-treated with a second course of SRS after local failure. A median dose of 20 Gy (range 14-22 Gy) was delivered to the tumor margin at the time of repeat SRS. Local control at 1 year was 79% (95% CI 67%-94%). Estimated 1-year OS was 70% (95% CI 55%-88%). Twelve patients had died at the most recent follow-up, with 8/12 patients experiencing neurological death (as described in Patchell et al.). Eleven of 46 (24%) lesions in 11 separate patients treated with repeat SRS were associated with symptomatic radiation necrosis. Freedom from radiation necrosis at 1 year was 71% (95% CI 57%-88%). Analysis of dosimetric data revealed that the volume of a lesion receiving 40 Gy (V_40Gy) was the most predictive factor for the development of radiation necrosis (p = 0.003). The following V_40Gy thresholds were associated with 10%, 20%, and 50% probabilities of radiation necrosis, respectively: 0.28 cm³ (95% CI 3%-28%), 0.76 cm³ (95% CI 9%-39%), 1.60 cm³ (95% CI 26%-74%). CONCLUSIONS Repeat SRS appears to be an effective salvage option for patients with brain metastases experiencing local failure following initial SRS treatment. This series demonstrates durable local control and, although rates of radiation necrosis are significant, repeat SRS may be indicated for select cases of local disease recurrence. Because the V_40Gy is predictive of radiation necrosis, limiting this value during treatment planning may allow for a reduction in radiation necrosis rates.

[Experience with the radiosurgical treatment of brain metastases]

OBJECTIVE

To analyse the survival rate of a cohort of patients with intracranial metastases treated with radiosurgery, and to determine the factors that influence the results.

PATIENTS AND METHOD

Retrospective analysis performed on a cohort of 126 patients undergoing radiosurgery for brain metastases. Patients treated with surgery before or after radiosurgery were excluded. Survival is analysed based on clinical (age, sex, primary tumour), radiological (number, location and volume of lesions), and radiotherapy factors (treatment dose, holocraneal radiation). Univariate and multivariate analyses were performed to determine significant prognostic factors.

RESULTS

A total of 225 brain metastases in 126 patients, with a mean age of 59.8±11.6years, were treated between February 2008 and April 2015. The mean survival was 8.2 months. The overall survival rates at 6months, 1year, and 2years were 60.3%, 31.5%, and 12.8%, respectively. Lung (59.5%) and breast (14.3) were the most common primary tumours, and the most common site for metastases was the cerebral hemisphere (77%) and the average volume was 10.35 cc (0.2-43.5). Significant survival factors were: age under 60 (P=.046), female (P<.001), breast cancer (P<.001), KPS >80 (P=.001), SIR6 >5 (P=.031), and GPA ≥2.5 (P=.003).

CONCLUSIONS

Radiosurgery is an appropriate technique for the treatment of brain metastases, and the main prognostic factors include being age under 65, female, breast cancer, and good scores on Karnofsky, SIR, and GPA scales.

Predicted survival in patients with brain metastases from colorectal cancer: Is a current nomogram helpful?

OBJECTIVE

To examine the clinical applicability of a new nomogram by comparing survival of patients with brain metastases from colorectal cancer treated with surgery and/or radiotherapy in the authors' institutions with nomogram-predicted median survival.

METHODS

Retrospective analysis of 64 patients treated with comparable approaches and during the same time period as the patients in the nomogram study. Points were assigned for age, performance status, number and site of brain metastases, as required for nomogram use.

RESULTS

In 46 patients (72%), the observed survival was shorter than the predicted median. The median deviation was -1.4 months. The nomogram underestimated the survival of patients treated with radiosurgery/surgery by a median of 4.2 months, whereas it overestimated the survival of patients treated with whole-brain radiotherapy (WBRT) by a median of 2.1 months (p=0.0001). Nevertheless, all 5 patients with predicted median survival ≤3 months died within 3 months. Among 8 patients with predicted median survival >12 months, 6 (75%) survived for >12 months. Not all prognostic factors in the nomogram correlated with survival. In the multivariate Cox model, only performance status and number of brain metastases were significant, both with p=0.0001.

CONCLUSION

Despite differences in prognostic factors and survival of many individual patients, especially those with intermediate prognosis, the nomogram performed promising in poor- and good-prognosis patients. Evaluation of separate prediction tools for patients treated with WBRT and more aggressive local approaches appears warranted in order to minimize the influence of better local control of the brain metastases.