Outcome of gamma knife radiosurgery for metastatic brain tumors derived from non-small cell lung cancer

Predicting Tumor Dynamics Post-Staged GKRS: Machine Learning Models in Brain Metastases Prognosis

This study assesses the predictive performance of six machine learning models and a 1D Convolutional Neural Network (CNN) in forecasting tumor dynamics within three months following Gamma Knife radiosurgery (GKRS) in 77 brain metastasis (BM) patients. The analysis meticulously evaluates each model before and after hyperparameter tuning, utilizing accuracy, AUC, and other metrics derived from confusion matrices. The CNN model showcased notable performance with an accuracy of 98% and an AUC of 0.97, effectively complementing the broader model analysis. Initial findings highlighted that XGBoost significantly outperformed other models with an accuracy of 0.95 and an AUC of 0.95 before tuning. Post-tuning, the Support Vector Machine (SVM) demonstrated the most substantial improvement, achieving an accuracy of 0.98 and an AUC of 0.98. Conversely, XGBoost showed a decline in performance after tuning, indicating potential overfitting. The study also explores feature importance across models, noting that features like "control at one year", "age of the patient", and "beam-on time for volume V1 treated" were consistently influential across various models, albeit their impacts were interpreted differently depending on the model's underlying mechanics. This comprehensive evaluation not only underscores the importance of model selection and hyperparameter tuning but also highlights the practical implications in medical diagnostic scenarios, where the accuracy of positive predictions can be crucial. Our research explores the effects of staged Gamma Knife radiosurgery (GKRS) on larger tumors, revealing no significant outcome differences across protocols. It uniquely considers the impact of beam-on time and fraction intervals on treatment efficacy. However, the investigation is limited by a small patient cohort and data from a single institution, suggesting the need for future multicenter research.

Can we predict overall survival using machine learning algorithms at 3-months for brain metastases from non-small cell lung cancer after gamma knife radiosurgery?

Gamma knife radiosurgery (GRKS) is widely used for patients with brain metastases; however, predictions of overall survival (OS) within 3-months post-GKRS remain imprecise. Specifically, more than 10% of non-small cell lung cancer (NSCLC) patients died within 8 weeks of post-GKRS, indicating potential overtreatment. This study aims to predict OS within 3-months post-GKRS using machine learning algorithms, and to identify prognostic features in NSCLC patients. We selected 120 NSCLC patients who underwent GKRS at Chungbuk National University Hospital. They were randomly assigned to training group (n = 80) and testing group (n = 40) with 14 features considered. We used 3 machine learning (ML) algorithms (Decision tree, Random forest, and Boosted tree classifier) to predict OS within 3-months for NSCLC patients. And we extracted important features and permutation features. Data validation was verified by physician and medical physicist. The accuracy of the ML algorithms for predicting OS within 3-months was 77.5% for the decision tree, 72.5% for the random forest, and 70% for the boosted tree classifier. The important features commonly showed age, receiving chemotherapy, and pretreatment each algorithm. Additionally, the permutation features commonly showed tumor volume (>10 cc) and age as critical factors each algorithm. The decision tree algorithm exhibited the highest accuracy. Analysis of the decision tree visualized data revealed that patients aged (>71 years) with tumor volume (>10 cc) were increased risk of mortality within 3-months. The findings suggest that ML algorithms can effectively predict OS within 3-months and identify crucial features in NSCLC patients. For NSCLC patients with poor prognoses, old age, and large tumor volumes, GKRS may not be a desirable treatment.

Stereotactic radiosurgery and resection for treatment of multiple brain metastases: a systematic review and analysis

OBJECTIVE

Stereotactic radiosurgery (SRS) has recently emerged as a minimally invasive alternative to resection for treating multiple brain metastases. Given the lack of consensus regarding the application of SRS versus resection for multiple brain metastases, the authors aimed to conduct a systematic literature review of all published work on the topic.

METHODS

The PubMed, OVID, Cochrane, Web of Science, and Scopus databases were used to identify studies that examined clinical outcomes after resection or SRS was performed in patients with multiple brain metastases. Radiological studies, case series with fewer than 3 patients, pediatric studies, or national database studies were excluded. Data extracted included patient demographics and mean overall survival (OS). Weighted t-tests and ANOVA were performed.

RESULTS

A total of 1300 abstracts were screened, 450 articles underwent full-text review, and 129 studies met inclusion criteria, encompassing 20,177 patients (18,852 treated with SRS and 1325 who underwent resection). The OS for the SRS group was 10.2 ± 6 months, and for the resection group it was 6.5 ± 3.8 months. A weighted ANOVA test comparing OS with covariates of age, sex, and publication year revealed that the treatment group (p = 0.045), age (p = 0.034), and publication year (0.0078) were all independently associated with OS (with SRS, younger age, and later publication year being associated with longer survival), whereas sex (p = 0.95) was not.

CONCLUSIONS

For patients with multiple brain metastases, SRS and resection are effective treatments to prolong OS, with published data suggesting that SRS may have a trend toward lengthened survival outcomes. The authors encourage additional work examining outcomes of treatments for multiple brain metastases.

The incidence and predictors of new brain metastases in patients with non-small cell lung cancer following discontinuation of systemic therapy

OBJECTIVE

Patients with non-small cell lung cancer (NSCLC) metastatic to the brain are living longer. The risk of new brain metastases when these patients stop systemic therapy is unknown. The authors hypothesized that the risk of new brain metastases remains constant for as long as patients are off systemic therapy.

METHODS

A prospectively collected registry of patients undergoing radiosurgery for brain metastases was analyzed. Of 606 patients with NSCLC, 63 met the inclusion criteria of discontinuing systemic therapy for at least 90 days and undergoing active surveillance. The risk factors for the development of new tumors were determined using Cox proportional hazards and recurrent events models.

RESULTS

The median duration to new brain metastases off systemic therapy was 16.0 months. The probability of developing an additional new tumor at 6, 12, and 18 months was 26%, 40%, and 53%, respectively. There were no additional new tumors 22 months after stopping therapy. Patients who discontinued therapy due to intolerance or progression of the disease and those with mutations in RAS or receptor tyrosine kinase (RTK) pathways (e.g., KRAS, EGFR) were more likely to develop new tumors (hazard ratio [HR] 2.25, 95% confidence interval [CI] 1.33-3.81, p = 2.5 × 10-3; HR 2.51, 95% CI 1.45-4.34, p = 9.8 × 10-4, respectively).

CONCLUSIONS

The rate of new brain metastases from NSCLC in patients off systemic therapy decreases over time and is uncommon 2 years after cessation of cancer therapy. Patients who stop therapy due to toxicity or who have RAS or RTK pathway mutations have a higher rate of new metastases and should be followed more closely.

Histopathology and surgical outcome of symptomatic treatment-related changes after gamma knife radiosurgery in patients with brain metastases

A late-onset treatment-related changes (TRCs), which represent radiographic radiation necrosis (RN), frequently occur after stereotactic radiosurgery (SRS) for brain metastases and often need surgical treatment. This study aimed to validate the true pathology and investigate clinical implication of surgically resected TRCs on advanced magnetic resonance imaging (MRI). Retrospective analyses of 86 patients who underwent surgical resection after radiosurgery of brain metastases were performed. Fifty-four patients displayed TRCs on preoperative MRI, comprising pure RN in 19 patients (TRC-RN group) and mixed viable tumor cells in 35 patients (TRC-PD group). Thirty-two patients revealed the consistent diagnosis of progressive disease in both MRI and histopathology (PD–PD group). The TRC-PD group showed larger prescription isodose volume (9.4 cm³) than the TRC-RN (4.06 cm³, p = 0.014) group and a shorter time interval from SRS to preoperative MRI diagnosis (median 4.07 months) than the PD–PD group (median 8.77 months, p = 0.004). Progression-free survival was significantly different among the three groups (p < 0.001), but not between TRC-RN and TRC-PD (post hoc test, p = 1.00), while no difference was observed in overall survival (p = 0.067). Brain metastases featured as TRCs after SRS frequently contained viable tumor cells. However, this histologic heterogeneity had a minor impact on benign local prognosis of TRCs after surgical resection.

Treatment for Brain Metastases: ASCO-SNO-ASTRO Guideline

PURPOSE

To provide guidance to clinicians regarding therapy for patients with brain metastases from solid tumors.

METHODS

ASCO convened an Expert Panel and conducted a systematic review of the literature.

RESULTS

Thirty-two randomized trials published in 2008 or later met eligibility criteria and form the primary evidentiary base.

RECOMMENDATIONS

Surgery is a reasonable option for patients with brain metastases. Patients with large tumors with mass effect are more likely to benefit than those with multiple brain metastases and/or uncontrolled systemic disease. Patients with symptomatic brain metastases should receive local therapy regardless of the systemic therapy used. For patients with asymptomatic brain metastases, local therapy should not be deferred unless deferral is specifically recommended in this guideline. The decision to defer local therapy should be based on a multidisciplinary discussion of the potential benefits and harms that the patient may experience. Several regimens were recommended for non-small-cell lung cancer, breast cancer, and melanoma. For patients with asymptomatic brain metastases and no systemic therapy options, stereotactic radiosurgery (SRS) alone should be offered to patients with one to four unresected brain metastases, excluding small-cell lung carcinoma. SRS alone to the surgical cavity should be offered to patients with one to two resected brain metastases. SRS, whole brain radiation therapy, or their combination are reasonable options for other patients. Memantine and hippocampal avoidance should be offered to patients who receive whole brain radiation therapy and have no hippocampal lesions and 4 months or more expected survival. Patients with asymptomatic brain metastases with either Karnofsky Performance Status ≤ 50 or Karnofsky Performance Status < 70 with no systemic therapy options do not derive benefit from radiation therapy.Additional information is available at www.asco.org/neurooncology-guidelines.

Immune Checkpoint Inhibitors for Non-Small-Cell Lung Cancer with Brain Metastasis : The Role of Gamma Knife Radiosurgery

Objective

Immune checkpoint inhibitors (ICIs) are approved for treating non-small-cell lung cancer (NSCLC); however, the safety and efficacy of combined ICI and Gamma Knife radiosurgery (GKS) treatment remain undefined. In this study, we retrospectively analyzed patients treated with ICIs with or without GKS at our institute to manage patients with brain metastases from NSCLC.

Methods

We retrospectively reviewed medical records of patients with brain metastases from NSCLC treated with ICIs between January 2015 and December 2017. Of 134 patients, 77 were assessable for brain responses and categorized into three groups as follows : group A, ICI alone (n=26); group B, ICI with concurrent GKS within 14 days (n=24); and group C, ICI with non-concurrent GKS (n=27).

Results

The median follow-up duration after brain metastasis diagnosis was 19.1 months (range, 1–77). At the last follow-up, 53 patients (68.8%) died, 20 were alive, and four were lost to follow-up. The estimated median overall survival (OS) of all patients from the date of brain metastasis diagnosis was 20.0 months (95% confidence interval, 12.5–27.7) (10.0, 22.5, and 42.1 months in groups A, B, and C, respectively). The OS was shorter in group A than in group C (p=0.001). The intracranial disease progression-free survival (p=0.569), local progression-free survival (p=0.457), and complication rates did not significantly differ among the groups. Twelve patients showed leptomeningeal seeding (LMS) during follow-up. The 1-year LMS-free rate in treated with ICI alone group (69.1%) was significantly lower than that in treated with GKS before ICI treatment or within 14 days group (93.2%) (p=0.004).

Conclusion

GKS with ICI showed no favorable OS outcome in treating brain metastasis from NSCLC. However, GKS with ICI did not increase the risk of complications. Furthermore, compared with ICI alone, GKS with ICI may be associated with a reduced incidence of LMS. Further understanding of the mechanism, which remains unknown, may help improve the quality of life of patients with brain metastasis.

Identification of Patients with Brain Metastases with Favorable Prognosis After Local and Distant Recurrence Following Stereotactic Radiosurgery

Purpose

This retrospective study aimed to determine the prognostic factors associated with overall survival after intracranial local and distant recurrence in patients undergoing stereotactic radiosurgery (SRS) for brain metastases.

Patients and Methods

Clinical characteristics and therapeutic parameters of 251 patients, who were treated with initial stereotactic radiosurgery for brain metastases and later experienced intracranial recurrence, were analyzed to identify prognostic factors of post-recurrence overall survival (PROS). A Cox proportional hazard model was applied for univariate and multivariate analyses.

Results

Among the 251 patients, the median post-recurrence overall survival was 8 months, and the six-month PROS rate was 60.2%. The interval from initial radiosurgery treatment to intracranial recurrence (hazard ratio [HR]:0.970), the number of brain recurrent tumors (HR:1.245), the number of extracranial metastatic organs (HR:1.183), recursive partition analysis (RPA) (HR:1.778), and Eastern Cooperative Oncology Group Performance Status (ECOG PS) (HR:2.442) were identified as independent prognostic factors. The patients who received local treatment for solitary brain recurrence achieved better survival (the median survival time after recurrence was 22 months). In patients without extracranial metastasis, the median post-recurrence overall survival of the local treatment group was longer than that in the whole brain radiation therapy (WBRT) group (P<0.001) and the systemic therapy group (P<0.001).

Conclusion

A shorter interval from initial stereotactic radiosurgery to recurrence, an increasing number of brain recurrences and extracranial metastatic organs, and poor RPA and ECOG PS values are associated with poor post-recurrence prognosis. When the number of brain recurrent tumors and extracranial metastatic organs was limited, local treatment including stereotactic radiosurgery, surgery or intensity-modulated radiation therapy (IMRT) improved the post-recurrence overall survival.

Magnetic Resonance-Guided Laser-Induced Thermal Therapy for the Treatment of Progressive Enhancing Inflammatory Reactions Following Stereotactic Radiosurgery, or PEIRs, for Metastatic Brain Disease

BACKGROUND

In patients who have previously undergone maximum radiation for metastatic brain tumors, a progressive enhancing inflammatory reaction (PEIR) that represents either tumor recurrence or radiation necrosis, or a combination of both, can occur. Magnetic resonance-guided laser-induced thermal therapy (LITT) offers a minimally invasive treatment option for this problem.

OBJECTIVE

To report our single-center experience using LITT to treat PEIRs after radiosurgery for brain metastases.

METHODS

Patients with progressive, enhancing reactions at the site of prior radiosurgery for metastatic brain tumors and who had a Karnofsky performance status of ≥70 were eligible for LITT. The primary endpoint was local control. Secondary end points included dexamethasone use and procedure-related complications.

RESULTS

Between 2010 and 2017, 59 patients who underwent 74 LITT procedures for 74 PEIRs met inclusion criteria. The mean pre-LITT PEIR size measured 3.4 ± 0.4 cm3. At a median follow-up of 44.6 wk post-LITT, the local control rate was 83.1%. Most patients were weaned off steroids post-LITT. Patients experiencing a post-LITT complication were more likely to remain on steroids indefinitely. The rate of new permanent neurological deficit was 3.4%.

CONCLUSION

LITT is an effective treatment for local control of PEIRs after radiosurgery for metastatic brain disease. When possible, we recommend offering LITT once PEIRs are identified and prior to the initiation of high-dose steroids for symptom relief.

The Effect of Epidermal Growth Factor Receptor Mutation on Intracranial Progression-Free Survival of Non-Small Cell Lung Cancer Patients with Brain Metastasis Underwent Gamma Knife Radiosurgery

BACKGROUND

The aim of this study was to survey prognostic factors, particularly those focusing on epidermal growth factor receptor (EGFR) mutations, of patients with non-small cell lung cancer (NSCLC) after Gamma Knife Radiosurgery (GKRS) for metastatic brain tumors.

METHODS

We retrospectively reviewed the medical records of 98 patients with NSCLC who underwent GKRS for brain metastases from August 2010 to July 2017. The primary endpoint was progression-free survival (PFS) of the intracranial disease. We analyzed variables such as age, sex, Karnofsky Performance Status, recursive partitioning analysis (RPA) class, smoking status, primary cancer pathology, EGFR mutations, and time to brain metastases as prognostic factors.

RESULTS

The median overall survival (OS) of the patients was 16 months [95% confidence interval (CI), 13-21 months]. Median systemic PFS and intracranial PFS were 9 months (95% CI, 8-11 months) and 11 months (95% CI, 7-14 months), respectively. Kaplan-Meier survival analysis revealed that the patients with EGFR mutations had longer intracranial PFS than those without EGFR mutation (median intracranial PFS: 19 vs. 10 months with p=0.01) while they had no benefits in OS and systemic PFS. Furthermore, the patients harboring adenocarcinoma had longer OS (p<0.01) and intracranial PFS (p<0.01) and the patients with lower RPA class had longer OS (p=0.02) and intracranial PFS (p=0.03).

CONCLUSION

EGFR mutations, primary cancer pathology, and RPA class may be proposed as prognostic factors for intracranial PFS in NSCLC patients after GKRS for brain metastasis in this study.

Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines on Treatment Options for Adults With Multiple Metastatic Brain Tumors

TARGET POPULATION

These recommendations apply to adult patients newly diagnosed with multiple (more than 1) brain metastases.

QUESTION 1

In what circumstances should whole brain radiation therapy be recommended to improve tumor control and survival in patients with multiple brain metastases?

RECOMMENDATION

Level 2: It is recommended that whole brain radiation therapy can be added to stereotactic radiosurgery to improve local and distant control keeping in mind the potential for worsened neurocognitive outcomes and that there is unlikely to be a significant impact on overall survival.

QUESTION 2

In what circumstances should stereotactic radiosurgery be recommended to improve tumor control and survival in patients with multiple brain metastases?

RECOMMENDATIONS

Level 1: In patients with 2 to 3 brain metastases not amenable to surgery, the addition of stereotactic radiosurgery to whole brain radiation therapy is not recommended to improve survival beyond that obtained with whole brain radiation therapy alone. Level 3: The use of stereotactic radiosurgery alone is recommended to improve median overall survival for patients with more than 4 metastases having a cumulative volume < 7 cc.

QUESTION 3

In what circumstances should surgery be recommended to improve tumor control and survival in patients with multiple brain metastases?

RECOMMENDATION

Level 3: In patients with multiple brain metastases, tumor resection is recommended in patients with lesions inducing symptoms from mass effect that can be reached without inducing new neurological deficit and who have control of their cancer outside the nervous system.The full guideline can be found at https://www.cns.org/guidelines/guidelines-treatment-adults-metastatic-brain-tumors/chapter_6.

Volumetric changes of intracranial metastases during the course of fractionated stereotactic radiosurgery and significance of adaptive planning

OBJECTIVE

Fractionated Gamma Knife surgery (FGKS) has recently been used to treat large brain metastases. However, little is known about specific volume changes of lesions during the course of treatment. The authors investigated short-term volume changes of metastatic lesions during FGKS.

METHODS

The authors analyzed 33 patients with 40 lesions who underwent FGKS for intracranial metastases of non-small-cell lung cancer (NSCLC; 25 patients with 32 lesions) and breast cancer (8 patients with 8 lesions). FGKS was performed in 3-5 fractions. Baseline MRI was performed before the first fraction. MRI was repeated after 1 or 2 fractions. Adaptive planning was executed based on new images. The median prescription dose was 8 Gy (range 6-10 Gy) with a 50% isodose line.

RESULTS

On follow-up MRI, 18 of 40 lesions (45.0%) showed decreased tumor volumes (TVs). A significant difference was observed between baseline (median 15.8 cm3) and follow-up (median 14.2 cm3) volumes (p < 0.001). A conformity index was significantly decreased when it was assumed that adaptive planning was not implemented, from baseline (mean 0.96) to follow-up (mean 0.90, p < 0.001). The average reduction rate was 1.5% per day. The median follow-up duration was 29.5 weeks (range 9-94 weeks). During the follow-up period, local recurrence occurred in 5 lesions.

CONCLUSIONS

The TV showed changes with a high dose of radiation during the course of FGKS. Volumetric change caused a significant difference in the clinical parameters. It is expected that adaptive planning would be helpful in the case of radiosensitive tumors such as NSCLCs or breast cancer to ensure an adequate dose to the target area and reduce unnecessary exposure of normal tissue to radiation.

The influence of histology on the response of brain metastases to gamma knife radiosurgery: a propensity score-matched study

BACKGROUND

In terms of response to fractionated radiotherapy, metastatic brain tumors of certain origins are considered radioresistant.

OBJECTIVE

To determine the influence of "radioresistant" histology on outcomes of brain metastases treated with radiosurgery.

METHODS

Between 2001 and 2017, 121 patients with brain metastases from renal cell carcinoma (RCC) and 2151 from non-small cell lung cancer (NSCLC) were reviewed. Eighty-seven pairs were derived using propensity score matching. Local progression-free survival (PFS), progression patterns, distant PFS, and overall survival were investigated.

RESULTS

The median follow-up period was 13.7 months (range, 1.6-78.4 months). A total of 536 lesions were treated using gamma knife radiosurgery (GKS), with a median dose of 20 Gy (range, 12-28 Gy). The actuarial local PFS rates in the RCC group were 91% and 89% at 6 and 12 months, respectively, and did not differ from the NSCLC group (97% and 83% at 6 and 12 months, respectively). Continuous progression, without response to GKS, was noted in seven of the eight progressed RCCs. However, six of the seven progressed NSCLCs showed transient shrinkage before progression. The median distant PFS was 9.3 months (95% CI, 6.3-12.2) in the RCC group and 8.0 months (95% CI, 5.5-10.4) in the NSCLC group. The median overall survival was 16.1 months (95% CI, 11.3-20.8) and 14.9 months (95% CI, 11.9-17.8) in RCC and NSCLC groups, respectively.

CONCLUSION

Histological differences had no effect on local control in the single high-dose range used for radiosurgery. However, changes in tumor volume during progression varied across tumor histology.

Repeat Stereotactic Radiosurgery for Recurred Metastatic Brain Tumors

OBJECTIVE

We investigated the outcomes of repeat stereotactic radiosurgery (SRS) for metastatic brain tumors that locally recurred despite previous SRS, focusing on the tumor control.

METHODS

A total of 114 patients with 176 locally recurring metastatic brain tumors underwent repeat SRS after previous SRS. The mean age was 59.4 years (range, 33 to 85), and there were 68 male and 46 female patients. The primary cancer types were non-small cell lung cancer (n=67), small cell lung cancer (n=12), gastrointestinal tract cancer (n=15), breast cancer (n=10), and others (n=10). The number of patients with a single recurring metastasis was 95 (79.8%), and another 19 had multiple recurrences. At the time of the repeat SRS, the mean volume of the locally recurring tumors was 5.94 mL (range, 0.42 to 29.94). We prescribed a mean margin dose of 17.04 Gy (range, 12 to 24) to the isodose line at the tumor border primarily using a 50% isodose line.

RESULTS

After the repeat SRS, we obtained clinical and magnetic resonance imaging follow-up data for 84 patients (73.7%) with a total of 108 tumors. The tumor control rate was 53.5% (58 of the 108), and the median and mean progression-free survival (PFS) periods were 246 and 383 days, respectively. The prognostic factors that were significantly related to better tumor control were prescription radiation dose of 16 Gy (p=0.000) and tumor volume less than both 4 mL (p=0.001) and 10 mL at the repeat SRS (p=0.008). The overall survival (OS) periods for all 114 patients after repeat SRS varied from 1 to 56 months, and median and mean OS periods were 229 and 404 days after the repeat SRS, respectively. The main cause of death was systemic problems including pulmonary dysfunction (n=58, 51%), and the identified direct or suspected brain-related death rate was around 20%.

CONCLUSION

The tumor control following repeat SRS for locally recurring metastatic brain tumors after a previous SRS is relatively lower than that for primary SRS. However, both low tumor volume and high prescription radiation dose were significantly related to the tumor control following repeat SRS for these tumors after previous SRS, which is a general understanding of primary SRS for metastatic brain tumors.

Predictors of quality of life and survival following Gamma Knife surgery for lung cancer brain metastases: a prospective study

OBJECTIVE

Lung cancer (LC) patients who develop brain metastases (BMs) have a poor prognosis. Estimations of survival and risk of treatment-related deterioration in quality of life (QOL) are important when deciding on treatment. Although we know of several prognostic factors for LC patients with BMs, the role of QOL has not been established. Authors of this study set out to evaluate changes in QOL following Gamma Knife surgery (GKS) for BMs in LC patients and QOL as a prognostic factor for survival.

METHODS

Forty-four of 48 consecutive LC patients with BMs underwent GKS in the period from May 2010 to September 2011, and their QOL was prospectively assessed before and 1, 3, 6, 9, and 12 months after GKS by using the Functional Assessment of Cancer Therapy–Brain (FACT-BR) questionnaire. A mixed linear regression model was used to identify potential predictive factors for QOL and to assess the effect of GKS and the disease course on QOL at follow-up.

RESULTS

Mean QOL as measured by the brain cancer subscale (BRCS) of the FACT-BR remained stable from baseline (score 53.0) up to 12 months post-GKS (57.1; p = 0.624). The BRCS score improved for 32 patients (72.3%) with a total BM volume ≤ 5 cm3. Mean improvement in these patients was 0.45 points each month of follow-up, compared to a decline of 0.50 points each month despite GKS treatment in patients with BM volumes > 5 cm3 (p = 0.04). Asymptomatic BMs (p = 0.01), a lower recursive partitioning analysis (RPA) classification (p = 0.04), and a higher Karnofsky Performance Scale (KPS) score (p < 0.01) at baseline were predictors for a high, stable QOL after GKS. After multivariate analysis, a high KPS score (p < 0.01) remained the only positive predictor of a high, stable QOL post-GKS.

Median survival post-GKS was 5.6 months (95% CI 1.0–10.3). A higher BRCS score (p = 0.01), higher KPS score (p = 0.01), female sex (p = 0.01), and the absence of liver (p = 0.02), adrenal (p = 0.02), and bone metastases (p = 0.03) predicted longer survival in unadjusted models. However, in multivariate analyses, a higher BRCS score (p < 0.01), female sex (p = 0.01), and the absence of bone metastases (p = 0.02) at GKS remained significant predictors. Finally, the BRCS score’s predictive value for survival was compared with the values for the variables behind well-known prognostic indices: age, KPS score, extracranial disease status, and number and volume of BMs. Both BRCS score (p = 0.01) and BM volume (p = 0.05) remained significant predictors for survival in the final model.

CONCLUSIONS

Patient-reported QOL according to the BRCS is a predictor of survival in patients with BMs and may be helpful in deciding on the optimal treatment. Gamma Knife surgery is a safe and effective therapeutic modality that improves QOL for LC patients with a BM volume ≤ 5 cm3 at treatment. Careful follow-up and salvage therapy on demand seem to prevent worsening of QOL due to relapse of BMs.

Evaluation of new lesions and symptoms after gamma knife radiosurgery for brain metastases: a retrospective cohort study

BACKGROUND

Symptomatic new lesions that appear after gamma knife radiosurgery (GKRS) for brain metastases have not been thoroughly described.

METHODS

Among 238 patients who underwent a single session of GKRS without whole-brain radiotherapy or surgery for brain metastases between 2009 and 2014, a total of 165 (69.3%) patients underwent follow-up magnetic resonance imaging (MRI). Their electrical health records were reviewed retrospectively. The median age was 68 years, and 62.4% patients were men. The median number of brain metastases was 2. The most frequent primary organ site was the lung (71.5%). Then, we evaluated predictors for the symptoms of new lesions.

RESULTS

New lesions and leptomeningeal dissemination were observed in 101 (61.2%) and 23 (14.2%) patients, respectively. The median number of new lesions was 2; moreover, 20 of 101 patients (19.8%) with new lesions had tumours with the largest diameters of > 1 cm. Among 101 patients with new lesions, 13 were symptomatic (12.9%). Patients with larger new lesions (> 1 cm of the largest diameter) experienced symptoms more frequently (odds ratio 7.6, P < 0.01). Symptoms resolved after salvage GKRS in seven of 11 patients who abided by the recommended follow-up MRI schedule. No significant risk factors were found for symptoms of new lesions.

CONCLUSIONS

The incidence of symptomatic new lesions that appeared after GKRS was low, and more than half of the patients showed improvements in their symptoms after salvage GKRS. However, careful MRI-based assessments and salvage GKRS are critical for the quality of life.

Identifying candidates for gamma knife radiosurgery among elderly patients with brain metastases

We investigated the outcomes of gamma knife radiosurgery (GKRS) for elderly patients (≥ 65 years) with brain metastases, and identified survival-associated factors. We retrospectively analyzed data from 115 patients treated with GKRS for 1-15 brain metastases. The median patient age was 72 years; most primary tumors were pulmonary (n = 83). The mean lesion volume was 2.1 ± 4.8 mL. A mean dose of 19.3 Gy was delivered to the mean 63.9% isodose line. The median overall survival (OS) was 5.3 months (95% confidence interval [CI] 3.5-7.1). During follow-up (median, 5.1 months), 91 patients died of primary cancer progression while 1 died of unknown causes. The 6- and 12-month local control rates were 94.9 and 88.1%, respectively. On multivariate analysis, female sex (p = 0.005, hazard ratio [HR] 0.533, 95% CI 0.343-0.827) and a controlled primary tumor (p < 0.001, HR 0.328, 95% CI 0.180-0.596) were significantly favorable prognostic factors. Of non-small cell lung cancer patients with EGFR mutations, 76.5% were women (p = 0.005). The median OS of EGFR-mutant and EGFR-wildtype patients were 19.1 and 4.7 months, respectively (p = 0.080). Brain metastases < 3 mL showed better local control rates after GKRS (p = 0.005). GKRS produces favorable outcomes in women with brain metastases who are ≥ 65 years and have controlled primary tumors. Such patients are therefore suitable candidates for GKRS.

Role of Gamma Knife® Radiosurgery for the Treatment of Brain Metastases from Gynecological Cancers

Objective: Gamma Knife^® (GK) (Elekta Instruments, Stockholm, Sweden) radiosurgery is well established for treatment of brain metastases. There are limited data on patients treated with GK from gynecological cancers. The authors sought to determine the effectiveness of the GK in patients with brain metastases from gynecological cancers.

Methods: An IRB-approved database was queried for patients with gynecologic cancers treated with GK between June 1996 and May 2016. Imaging studies were reviewed post-SRS (stereotactic radiosurgery) to evaluate local control (LC) and distant brain control (DC). Overall survival (OS), local control, and distant brain control were calculated using the Kaplan-Meier (KM) method and log-rank test. 

Results: Thirty-three patients underwent SRS for 73 separate cranial lesions. The median age was ­58.5 years, and 17 (52%) also had extracranial metastases. Ten (30%) patients had previously received whole brain radiotherapy (WBRT), and 11 (33%) underwent concurrent WBRT. The median tumor volume was 0.96 cm³. Median radiographic follow-up was 11 months. At the time of treatment, 39% of patients were categorized as recursive partitioning analysis (RPA) Class I, 55% as RPA Class II, and 6% as RPA Class III. The local failure rate was 8%. Five patients (15%) developed new brain lesions outside the radiation field with a median progression-free survival (PFS) of seven (range: 3-9) months. Median OS was 15 months from GK treatment. One-year OS was 72.9% from GK treatment. Primary cancer histology was a significant predictor of OS, favoring ovarian and endometrial cancer (p = 0.03).

Conclusions: Gamma Knife stereotactic radiosurgery for gynecologic brain metastases leads to excellent control rates of treated lesions. Primary histology may have a significant impact on OS following GK, with improved survival seen with ovarian and cervical cancer following Gamma Knife radiosurgery (p = 0.03).

The Influence of Biomarker Mutations and Systemic Treatment on Cerebral Metastases from NSCLC Treated with Radiosurgery

Objective

The purpose of this study was to analyze outcomes and identify prognostic factors in patients with cerebral metastases from non-small cell lung cancer (NSCLC) treated with gamma knife radiosurgery (GKS) particularly, focusing on associations of biomarkers and systemic treatments.

Methods

We retrospectively reviewed the medical records of 134 patients who underwent GKS for brain metastases due to NSCLC between January 2002 and December 2012. Representative biomarkers including epidermal growth factor receptor (EGFR) mutation, K-ras mutation, and anaplastic lymphoma kinase (ALK) mutation status were investigated.

Results

The median overall survival after GKS was 22.0 months (95% confidence interval [CI], 8.8–35.1 months). During follow-up, 63 patients underwent salvage treatment after GKS. The median salvage treatment-free survival was 7.9 months (95% CI, 5.2–10.6 months). Multivariate analysis revealed that lower recursive partition analysis (RPA) class, small number of brain lesions, EGFR mutation (+), and ALK mutation (+) were independent positive prognostic factors associated with longer overall survival. Patients who received target agents 30 days after GKS experienced significant improvements in overall survival and salvage treatment-free survival than patients who never received target agents and patients who received target agents before GKS or within 30 days (median overall survival: 5.0 months vs. 18.2 months, and 48.0 months with p-value=0.026; median salvage treatment-free survival: 4.3 months vs. 6.1 months and 16.6 months with p-value=0.006, respectively). To assess the influence of target agents on the pattern of progression, cases that showed local recurrence and new lesion formation were analyzed according to target agents, but no significant effects were identified.

Conclusion

The prognosis of patients with brain metastases of NSCLC after GKS significantly differed according to specific biomarkers (EGFR and ALK mutations). Our results show that target agents combined with GKS was related to significantly longer overall survival, and salvage treatment-free survival. However, target agents were not specifically associated with improved local control of the lesion treated by GKS either development of new lesions. Therefore, it seems that currently popular target agents do not affect brain lesions themselves, and can prolong survival by controlling systemic disease status.

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.