Predictors for long-term survival free from whole brain radiation therapy in patients treated with radiosurgery for limited brain metastases

Association of Brain Metastases With Survival in Patients With Limited or Stable Extracranial Disease: A Systematic Review and Meta-analysis

IMPORTANCE

Intracranial metastatic disease (IMD) is a severe complication of cancer with profound prognostic implications. Patients with IMD in the setting of limited or stable extracranial disease (IMD-SE) may represent a unique and understudied subset of patients with IMD with superior prognosis.

OBJECTIVE

To evaluate overall survival (OS), progression-free survival (PFS), and intracranial PFS (iPFS) in patients with IMD-SE secondary to any primary cancer.

DATA SOURCES

Records were identified from MEDLINE, EMBASE, CENTRAL, and gray literature sources from inception to June 21, 2021.

STUDY SELECTION

Studies in English reporting OS, PFS, or iPFS in patients with IMD-SE (defined as IMD and ≤2 extracranial metastatic sites) and no prior second-line chemotherapy or brain-directed therapy were selected.

DATA EXTRACTION AND SYNTHESIS

Author, year of publication, type of study, type of primary cancer, and outcome measures were extracted. Random-effects meta-analyses were performed to estimate effect sizes, and subgroup meta-analysis and metaregression were conducted to measure between-study differences in February 2022.

MAIN OUTCOMES AND MEASURES

The primary end point was OS described as hazard ratios (HRs) and medians for comparative and single-group studies, respectively. Secondary end points were PFS and iPFS.

RESULTS

Overall, 68 studies (5325 patients) were included. IMD-SE was associated with longer OS (HR, 0.52; 95% CI, 0.39-0.70) and iPFS (HR, 0.63; 95% CI, 0.52-0.76) compared with IMD in the setting of progressive extracranial disease. The weighted median OS estimate for patients with IMD-SE was 17.9 months (95% CI, 16.4-22.0 months), and for patients with IMD-PE it was 8.0 months (95% CI, 7.2-12.8 months). Pooled median OS for all patients with IMD-SE was 20.9 months (95% CI, 16.35-25.98 months); for the subgroup with breast cancer it was 20.2 months (95% CI, 10.43-38.20 months), and for non-small cell lung cancer it was 27.5 months (95% CI, 18.27-49.66 months). Between-study heterogeneity for OS and iPFS were moderate (I2 = 56.5%) and low (I2 = 0%), respectively.

CONCLUSIONS AND RELEVANCE

In this systematic review and meta-analysis of patients with IMD-SE, limited systemic disease was associated with improved OS and iPFS. Future prospective trials should aim to collect granular information on the extent of extracranial disease to identify drivers of mortality and optimal treatment strategies in patients with brain metastases.

Brain metastases treated with radiosurgery or hypofractionated stereotactic radiotherapy: outcomes and predictors of survival

INTRODUCTION

To assess treatment outcome and prognostic factors associated with prolonged survival in patients with brain metastases (BM) treated with stereotactic radiosurgery (SRS) or hypofractionated stereotactic radiotherapy (HFSRT).

METHODS/PATIENTS

This study retrospectively reviewed 200 patients with 324 BM treated with one fraction (15-21 Gy) or 5-10 fractions (25-40 Gy) between January 2010 and August 2016. 26.5% of patients received whole brain radiotherapy (WBRT) and 25% initial surgery. Demographics, prognostic scales, systemic and local controls, patterns of relapse and rescue, toxicity, and cause of death were analyzed. A stratified analysis by primary tumor was done.

RESULTS

Median overall survival (OS) was 8 months from SRS/HFSRT. Breast cancer patients had a median OS of 17 months, followed by renal (11 months), lung (8 months), colorectal (5 months), and melanoma (4 months). The univariate analysis showed improved OS in females (p 0.004), RPA I-II (p < 0.001) initial surgery (p < 0.001), absence of extracranial disease (p 0.023), and good disease control (p 0.002). There were no differences in OS or local control between SRS and HFSRT or in patients receiving WBRT. Among 44% of brain recurrences, 11% were in field. 174 patients died, 10% from confirmed intracranial progression.

CONCLUSIONS

SRS and HSFRT are equally effective and safe for the treatment of BM, with no exceptions among different primary tumors. Disease control, surgery, age, and prognostic scales correlated with OS. However, the lack of survival benefit regarding WBRT might become logical evidence for its omission in a subset of patients.

Tumor volume and sphericity as predictors of local control after stereotactic radiosurgery for limited number (1-4) brain metastases from nonsmall cell lung cancer

AIM

This study aims to evaluate the usage of brain metastases (BM) tumor volume and sphericity as prognostic factors in local control (LC) after stereotactic radiosurgery (SRS) for limited number (1-4) BM from nonsmall cell lung cancer (NSCLC).

METHODS

We retrospectively reviewed 80 patients, with 141 BM, who were treated with SRS from 2012 to 2017. Local failure was defined as an increase in lesion size after SRS. LC and overall survival (OS) were estimated using Kaplan-Meier method. The Cox proportional hazards model was used for univariate and multivariate analysis.

RESULTS

The median clinical and radiographic follow-up was 11.2 and 9.0 months, respectively. The median BM tumor volume was 0.31 cm³ (0.01-21.64 cm³ ) and the median tumor sphericity was 0.76 (0.39-0.95). The median LC of the entire cohort was 28.8 months. LC rate at last follow-up was achieved in 84.4% of patients (35.5% CR, 35.5% PR, and 13.5% SD). LC was 83.8% at 1 year and 56.3% at 2 years. On multivariate analysis, only sphericity (P < .001) and volume (P = .004) were found to be a strong predictor for LC. The median OS of the entire cohort was 24.1 months. On multivariate analysis, only GPA score was found to be a predictor for OS.

CONCLUSION

BM tumor sphericity and volume were found to be strong predictors for LC. Tumor sphericity and volume should be taken into consideration when treating patients with BM and when designing future prospective studies and developing prognostic indices.

Multi-institutional competing risks analysis of distant brain failure and salvage patterns after upfront radiosurgery without whole brain radiotherapy for brain metastasis

Background

In this study, we use a competing risks analysis to assess factors predictive of early-salvage whole brain radiotherapy (WBRT) and early death after upfront stereotactic radiosurgery (SRS) alone for brain metastases in an attempt to identify populations that benefit less from upfront SRS.

Patients and methods

Patients from eight academic centers were treated with SRS for brain metastasis. Competing risks analysis was carried out for distant brain failure (DBF) versus death prior to DBF as well as for salvage SRS versus salvage WBRT versus death prior to salvage. Linear regression was used to determine predictors of the number of brain metastases at initial DBF (nDBF).

Results

A total of 2657 patients were treated with upfront SRS alone. Multivariate analysis (MVA) identified an increased hazard of DBF associated with increasing number of brain metastases (P < 0.001), lowest SRS dose received (P < 0.001), and melanoma histology (P < 0.001), while there was a decreased hazard of DBF associated with increasing age (P < 0.001), KPS < 70 (P < 0.001), and progressive systemic disease (P = 0.004). MVA for first salvage SRS versus WBRT versus death prior to salvage revealed an increased hazard of first salvage WBRT seen with increasing number of brain metastases (P < 0.001) and a decreased hazard with widespread systemic disease (P = 0.002) and increasing age (P < 0.001). Variables associated with nDBF included age (P = 0.02), systemic disease status (P = 0.03), melanoma histology (P = 0.05), and initial number of brain metastases (P < 0.001).

Conclusions

Patients with a higher initial number of brain metastases were more likely to experience DBF, have a higher nDBF, and receive early-salvage WBRT, while patients who were older, had lower KPS, or had more systemic disease were more likely to experience death prior to DBF or salvage WBRT.

Repeated Courses of Radiosurgery for New Brain Metastases to Defer Whole Brain Radiotherapy: Feasibility and Outcome With Validation of the New Prognostic Metric Brain Metastasis Velocity

Purpose: Stereotactic radiosurgery (SRS) is the preferred primary treatment option for patients with a limited number of asymptomatic brain metastases. In case of relapse after initial SRS the optimal salvage treatment is not well defined. Within this retrospective analysis, we investigated the feasibility of repeated courses of SRS to defer Whole-Brain Radiation Therapy (WBRT) and aimed to derive prognostic factors for patient selection. Materials and Methods: From 2014 until 2017, 42 patients with 197 brain metastases have been treated with multiple courses of SRS at our institution. Treatment was delivered as single fraction (18 or 20 Gy) or hypo-fractionated (6 fractions with 5 Gy) radiosurgery. Regular follow-up included clinical examination and contrast-enhanced cMRI at 3-4 months' intervals. Besides clinical and treatment related factors, brain metastasis velocity (BMV) as a newly described clinical prognostic metric was included and calculated between first and second treatment. Results: A median number of 1 lesion (range: 1-13) per course and a median of 2 courses (range: 2-6) per patient were administered resulting in a median of 4 (range: 2-14) metastases treated over time per patient. The median interval between SRS courses was 5.8 months (range: 0.9-35 months). With a median follow-up of 17.4 months (range: 4.6-45.5 months) after the first course of treatment, a local control rate of 84% was observed after 1 year and 67% after 2 years. Median time to out-of-field-brain-failure (OOFBF) was 7 months (95%CI 4-8 months). WBRT as a salvage treatment was eventually required in 7 patients (16.6%). Median overall survival (OS) has not been reached. Grouped by ds-GPA (≤ 2 vs. >2) the survival curves showed a significant split (p = 0.039). OS differed also significantly between BMV-risk groups when grouped into low vs. intermediate/high risk groups (p = 0.025). No grade 4 or 5 acute or late toxicity was observed. Conclusion: In selected patients with relapse after SRS for brain metastases, repeat courses of SRS were safe and minimized the need for rescue WBRT. The innovative, yet easy to calculate metric BMV may facilitate treatment decisions as a prognostic factor for OS.

Clinical factors associated with mortality within three months after radiosurgery of asymptomatic brain metastases from non-small cell lung cancer

PURPOSE

Routine brain MRI surveillance frequently diagnoses small, asymptomatic brain metastases from non-small cell lung cancer (NSCLC) that are effectively treated with stereotactic radiosurgery (SRS). A subset of patients, however, may die prior to the onset of symptoms. This study identifies clinical features that distinguish neurologically-asymptomatic NSCLC brain metastases patients that die prior to routine 3 month follow-up after SRS.

METHODS

Retrospective chart review from 2007 to 2017 identified 18 patients with neurologically-asymptomatic NSCLC brain metastases who died < 3 months after SRS. Twenty-eight additional patients meeting criteria and surviving > 6 months after SRS were identified. Clinical factors were examined to determine characteristics correlated with survival using cox proportional hazards and nominal logistic regression models. Logistic regression models using salient factors were trained with 10-fold cross-validation and compared to the graded prognostic assessment (GPA) and score index of radiosurgery (SIR) using the AUC from receiver operant characteristic curves.

RESULTS

The median survival following SRS was 1.4 and 9.2 months for the < 3 months and > 6 months groups, respectively. Age, number of brain metastases, and Karnofsky performance status were associated with overall survival while gender and interval between primary cancer and first brain metastasis diagnoses were associated with < 3 months and > 6 months survival, respectively. Models using GPA and SIR performed poorly compared to preliminary metrics generated in this study for prognosis of both < 3 months and > 6 months survival.

CONCLUSION

Physicians require data to provide high-value, cost-conscious health care. Clinical metrics can screen patients with asymptomatic NSCLC brain metastases likely to die prior to the standard screening interval and observation could be considered.

Onco-metabolism: defining the prognostic significance of obesity and diabetes in women with brain metastases from breast cancer

PURPOSE

Metabolic dysregulation has been implicated as a molecular driver of breast cancer in preclinical studies, especially with respect to metastases. We hypothesized that abnormalities in patient metabolism, such as obesity and diabetes, may drive outcomes in breast cancer patients with brain metastases.

METHODS

We retrospectively identified 84 consecutive patients with brain metastases from breast cancer treated with intracranial radiation therapy. Radiation was delivered as whole-brain radiation to a median dose of 3000 cGy or stereotactic radiosurgery to a median dose of 2100 cGy. Kaplan Meier curves were generated for overall survival (OS) data and Mantel-Cox regression was performed to detect differences in groups.

RESULTS

At analysis, 81 survival events had occurred and the median OS for the entire cohort was 21.7 months. Despite similar modified graded prognostic assessments, resection rates, and receptor status, BMI ≥ 25 kg/m² (n = 45) was associated with decreased median OS (13.7 vs. 30.6 months; p < 0.001) and median intracranial progression-free survival (PFS) (7.4 vs. 10.9 months; p = 0.04) compared to patients with BMI < 25 kg/m² (n = 39). Similar trends were observed among all three types of breast cancer. Patients with diabetes (n = 17) had decreased median OS (11.8 vs. 26.2 months; p < 0.001) and median intracranial PFS (4.5 vs. 10.3 months; p = 0.001) compared to non-diabetics (n = 67). On multivariate analysis, both BMI ≥ 25 kg/m² [HR 2.35 (1.39-3.98); p = 0.002] and diabetes [HR 2.77 (1.454-5.274); p = 0.002] were associated with increased mortality.

CONCLUSIONS

Elevated BMI or diabetes may negatively impact both overall survival and local control in patients with brain metastases from breast cancer, highlighting the importance of the translational development of therapeutic metabolic interventions. Given its prognostic significance, BMI should be used as a stratification in future clinical trial design in this patient population.

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

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

Evaluation of Prognostic Factors for Early Mortality After Stereotactic Radiosurgery for Brain Metastases: a Single Institutional Retrospective Review

BACKGROUND

Stereotactic radiosurgery (SRS) is used commonly for patients with brain metastases (BM) to improve intracranial disease control. However, survival of these patients is often dictated by their systemic disease course. The value of SRS becomes less clear in patients with anticipated short survival.

OBJECTIVE

To evaluate prognostic factors, which may predict early death (within 90 d) after SRS.

METHODS

A total of 1427 patients with BM were treated with SRS at our institution (2000-2012). There were 1385 cases included in this study; 1057 patients underwent upfront SRS and 328 underwent salvage SRS. The primary endpoint of the study was all-cause mortality within 90 d after first SRS. Multivariate analyses were performed to develop prognostic indices.

RESULTS

Two hundred sixty-six patients (19%, 95% confidence interval 17%-21%) died within 90 d after SRS. Multivariate analysis of upfront SRS patients showed that Karnofsky Performance Status, primary tumor type, extracranial metastases, age at SRS, boost treatment, total tumor volume, prior surgery, and interval from primary to BM were independent prognostic factors for 90-d mortality. The first 4 factors were also independent predictors in patients treated with salvage SRS. Based on these factors, an index was defined for each group that categorized patients into 3 and 2 prognostic groups, respectively. Ninety-day mortality was 5% to 7% in the most favorable cohort and 36% to 39% in the least favorable.

CONCLUSION

Indices based on readily available patient, clinical, and treatment factors that are highly predictive of early death in patients treated with upfront or salvage SRS can be calculated and used to define well-separated prognostic groups.

Patients with Long-Term Control of Systemic Disease Are a Favorable Prognostic Group for Treatment of Brain Metastases with Stereotactic Radiosurgery Alone

BACKGROUND

Stereotactic radiosurgery (SRS) alone is an attractive option for treatment of brain metastases. SRS avoids whole-brain radiotherapy (WBRT)-associated morbidity, but is limited by regional central nervous system (CNS) failures and short survival in some patients. We evaluated a subgroup of patients with controlled systemic disease that could represent a favorable patient population for SRS alone.

METHODS

All patients with brain metastases treated with SRS without WBRT at our institution between 2004 and 2014 were grouped into two cohorts: those with controlled systemic disease (CSD) for 1 year or longer before prior to presentation with brain metastases and those without (i.e., uncontrolled systemic disease [USD]). Rates of local and regional CNS failure, and overall survival were assessed with χ² and Student t tests. Cox regression analysis was performed to evaluate independent predictors of regional control and overall survival.

RESULTS

Two hundred ninety-four patients underwent SRS to 697 lesions, of which 65 patients had CSD. Median follow-up was 9.7 months. There was no difference in local control between the two cohorts (P = 0.795). Regional CNS control was significantly better for patients with CSD (68% vs. 48%; P = 0.001). Overall survival at 1 and 5 years for CSD were 65% and 13% with USD yielding 41% and 7%, respectively (P < 0.001). Multivariate analysis demonstrated that USD (relative CSD) independently predicts regional failure (hazard ratio [HR], 1.75; P = 0.008) and shorter overall survival (HR, 1.55; P = 0.007).

CONCLUSIONS

Patients with brain metastases after 1 year or longer of primary and systemic disease control represent a particularly favorable cohort, with lower regional CNS failure and prolonged survival, for an approach of SRS alone.

Brain metastasis in breast cancer: a comprehensive literature review

This comprehensive review provides information on epidemiology, size, grade, cerebral localization, clinical symptoms, treatments, and factors associated with longer survival in 14,599 patients with brain metastasis from breast cancer; the molecular features of breast cancers most likely to develop brain metastases and the potential use of these predictive molecular alterations for patient management and future therapeutic targets are also addressed. The review covers the data from 106 articles representing this subject in the era of modern neuroimaging (past 35 years). The incidence of brain metastasis from breast cancer (24 % in this review) is increasing due to advances in both imaging technologies leading to earlier detection of the brain metastases and introduction of novel therapies resulting in longer survival from the primary breast cancer. The mean age at the time of breast cancer and brain metastasis diagnoses was 50.3 and 48.8 years respectively. Axillary node metastasis was noted in 32.8 % of the patients who developed brain metastasis. The median time intervals between the diagnosis of breast cancer to identification of brain metastasis and from identification of brain metastasis to death were 34 and 15 months, respectively. The most common symptoms experienced in patients with brain metastasis consisted of headache (35 %), vomiting (26 %), nausea (23 %), hemiparesis (22 %), visual changes (13 %) and seizures (12 %). A majority of the patients had multiple metastases (54.2 %). Cerebellum and frontal lobes were the most common sites of metastasis (33 and 16 %, respectively). Of the primary tumors for which biomarkers were recorded, 37 % were estrogen receptor (ER)+, 41 % ER-, 36 % progesterone receptor (PR)+, 34 % PR-, 35 % human epithelial growth factor receptor 2 (HER2)+, 41 % HER2-, 27 % triple negative and 18 % triple positive (TP). Treatment in most patients consisted of a multimodality approach often with two or more of the following: whole brain radiation therapy (52 %), chemotherapy (51 %), stereotactic radiosurgery (20 %), surgical resection (14 %), trastuzumab (39 %) for HER2 positive tumors, and hormonal therapy (34 %) for ER and/or PR positive tumors. Factors that had an impact on prognosis included grade and size of the tumor, multiple metastases, presence of extra-cranial metastasis, triple negative or HER2+ biomarker status, and high Karnovsky score. Novel therapies such as application of agents to reduce tumor angiogenesis or alter permeability of the blood brain barrier are being explored with preliminary results suggesting a potential to improve survival after brain metastasis. Other potential therapies based on genetic alterations in the tumor and the microenvironment in the brain are being investigated; these are briefly discussed.