Brain metastases in metastatic cancer: a review of recent advances in systemic therapies

Brain metastasis screening in the molecular age

The incidence of brain metastases (BM) amongst cancer patients has been increasing due to improvements in therapeutic options and an increase in overall survival. Molecular characterization of tumors has provided insights into the biology and oncogenic drivers of BM and molecular subtype-based screening. Though there are currently some screening and surveillance guidelines for BM, they remain limited. In this comprehensive review, we review and present epidemiological data on BM, their molecular characterization, and current screening guidelines. The molecular subtypes with the highest BM incidence are epithelial growth factor receptor-mutated non-small cell lung cancer (NSCLC), BRCA1, triple-negative (TN), and HER2+ breast cancers, and BRAF-mutated melanoma. Furthermore, BMs are more likely to present asymptomatically at diagnosis in oncogene-addicted NSCLC and BRAF-mutated melanoma. European screening standards recommend more frequent screening for oncogene-addicted NSCLC patients, and clinical trials are investigating screening for BM in hormone receptor+, HER2+, and TN breast cancers. However, more work is needed to determine optimal screening guidelines for other primary cancer molecular subtypes. With the advent of personalized medicine, molecular characterization of tumors has revolutionized the landscape of cancer treatment and prognostication. Incorporating molecular characterization into BM screening guidelines may allow physicians to better identify patients at high risk for BM development and improve patient outcomes.

Evaluation of Whole Brain Radiotherapy among Lung Cancer Patients with Brain Metastases in Relation to Health Care Level and Survival

Whole-brain radiotherapy (WBRT) as a treatment for brain metastases has been questioned over the last years. This study aimed to evaluate health care levels and survival after WBRT in a cohort of lung cancer patients with brain metastases receiving WBRT in Stockholm, Sweden, from 2008 to 2019 (n = 384). If the patients were able to come home again was estimated using logistic regression and odds ratios (OR) and survival by using Cox regression. The median age in the cohort was 65.6 years, the median survival following WBRT was 2.4 months (interquartile range (IQR) 1.2–6.2 months), and 84 (22%) patients were not able to come home after treatment. Significantly more males could come home again after WBRT compared to women (OR = 0.37, 95%CI 0.20–0.68). Patients with performance status scores WHO 3–4 had a median survival of 1.0 months, hazard ratio (HR) = 4.69 (95%CI 3.31–6.64) versus WHO score 0–1. Patients admitted to a palliative ward before WBRT had a median survival of 0.85 months, HR = 2.26 (95%CI 1.53–3.34) versus being at home. In conclusion, patients treated with WBRT had a short median survival and 20% could not be discharged from the hospital following treatment. Significantly more women did not come home again.

Improving Brain Metastases Outcomes Through Therapeutic Synergy Between Stereotactic Radiosurgery and Targeted Cancer Therapies

Brain metastases are the most common form of brain cancer. Increasing knowledge of primary tumor biology, actionable molecular targets and continued improvements in systemic and radiotherapy regimens have helped improve survival but necessitate multidisciplinary collaboration between neurosurgical, medical and radiation oncologists. In this review, we will discuss the advances of targeted therapies to date and discuss findings of studies investigating the synergy between these therapies and stereotactic radiosurgery for non-small cell lung cancer, breast cancer, melanoma, and renal cell carcinoma brain metastases.

Changing characteristics, treatment approaches and survival of patients with brain metastasis: data from six thousand and thirty-one individuals over an observation period of 30 years

BACKGROUND

An accurate classification of patients with brain metastases (BMs) is an important foundation to guide individualised treatment decisions and to formulate BM cohorts for modern clinical trials.

METHODS

Six thousand and thirty-one patients with newly diagnosed BM from different solid tumours treated between 1986 and 2020 were identified from the Vienna Brain Metastasis Registry.

RESULTS

A rising fraction of patients presented with asymptomatic BM during the observation period (1986-1999: 20.2% vs 2010-2020: 30.6%; p < 0.001). Especially, oncogene-addicted non-small-cell lung cancer (NSCLC) and BRAF (v-Raf murine sarcoma viral oncogene homolog)-positive melanoma had a higher rate of asymptomatic BM presentation compared with wild-type tumours (p < 0.05). Significant changes of initial BM treatment approaches were observed with a decrease of neurosurgical procedures (1986-1999: 30.8% vs 2010-2020: 19.5%) and an increase of radiation treatments (1986-1999: 65.0% vs 2010-2020: 73.3%) and systemic therapies (1986-1999: 1.0% vs 2010-2020: 2.0%; p < 0.001). Median overall survival (OS) was heterogeneous between primary tumour entities but with an overall increase over the decades (median OS 1986-1999: 5 months vs 2010-2020: 7 months; p = 0.001). Survival times were longer in patients with oncogene-addicted NSCLC, BRAF-positive melanoma and hormone receptor-positive breast cancer compared with the other cancer subtypes (p > 0.05).

CONCLUSION

Our data highlight shifting trends in the symptomatic presentation and in treatment strategies of patients with BM over the last decades. Entity specific aspects and, in particular, the presence of targetable driver mutation impact the clinical presentation and prognosis. Future BM specific trials need to address the modern composition of BM cohorts and the distinct clinical course of patients with targetable driver mutations.

Brain metastases: the role of clinical imaging

Imaging of brain metastases (BMs) has advanced greatly over the past decade. In this review, we discuss the main challenges that BMs pose in clinical practice and describe the role of imaging.Firstly, we describe the increased incidence of BMs of different primary tumours and the rationale for screening. A challenge lies in selecting the right patients for screening: not all cancer patients develop BMs in their disease course.Secondly, we discuss the imaging techniques to detect BMs. A three-dimensional (3D) T1W MRI sequence is the golden standard for BM detection, but additional anatomical (susceptibility weighted imaging, diffusion weighted imaging), functional (perfusion MRI) and metabolic (MR spectroscopy, positron emission tomography) information can help to differentiate BMs from other intracranial aetiologies.Thirdly, we describe the role of imaging before, during and after treatment of BMs. For surgical resection, imaging is used to select surgical patients, but also to assist intraoperatively (neuronavigation, fluorescence-guided surgery, ultrasound). For treatment planning of stereotactic radiosurgery, MRI is combined with CT. For surveillance after both local and systemic therapies, conventional MRI is used. However, advanced imaging is increasingly performed to distinguish true tumour progression from pseudoprogression.FInally, future perspectives are discussed, including radiomics, new biomarkers, new endogenous contrast agents and theranostics.

Breast Cancer Subtypes and Mortality of Breast Cancer Patients With Brain Metastasis at Diagnosis: A Population-Based Study

Background

Brain metastasis is an important cause of breast cancer-related death.

Aim

We evaluated the relationships between breast cancer subtype and prognosis among patients with brain metastasis at the initial diagnosis.

Methods

The Surveillance, Epidemiology, and End Results database was searched to identify patients with brain metastasis from breast cancer between 2010 and 2015. Multivariable Cox proportional hazard models were used to identify factors that were associated with survival among patients with initial brain metastases. The Kaplan–Meier method was used to compare survival outcomes according to breast cancer subtype.

Results

Among 752 breast cancer patients with brain metastasis at diagnosis, 140 patients (18.6%) underwent primary surgery and 612 patients (81.4%) did not undergo surgery, while 460 patients (61.2%) received chemotherapy and 292 patients (38.8%) did not receive chemotherapy. Multivariable analysis revealed that, relative to HR+/HER2– breast cancer, HR–/HER2– breast cancer was associated with significantly poorer overall survival (hazard ratio: 2.52, 95% confidence interval: 1.99–3.21), independent of age, sex, race, marital status, insurance status, grade, liver involvement, lung involvement, primary surgery, radiotherapy, and chemotherapy. The median overall survival intervals were 12 months for HR+/HER2−, 19 months for HR+/HER2+, 11 months for HR−/HER2+, and 6 months for HR–/HER2– (P < .0001). Relative to HR+/HER2– breast cancer, HR–/HER2– breast cancer was associated with a significantly higher risk of mortality among patients, and the association was stronger among patients who received chemotherapy (p for interaction = .005).

Conclusions

Breast cancer subtype significantly predicted overall survival among patients with brain metastasis at diagnosis.

Precision medicine biomarkers in brain metastases: applications, discordances, and obstacles

Brain metastases (BM) present a common cause of mortality and morbidity in several metastatic cancer entities. New therapeutic developments during the last decades, including targeted and immune-related therapies, have shown considerable extra- and intracranial response rates in specific subgroups of BM patients. However, differences in the molecular alteration in the BM tumor tissue compared to extracranial tumors leads to heterogeneous therapeutic responses. Therefore, an accurate molecular analyzation of BM tissue, if possible, has become an essential part in therapeutic decision making in BM patients. The concordance of predictive molecular biomarkers between multiple sites including extracranial and intracranial tumor tissue have been analyzed for some but not all biomarkers routinely applied in modern precision medicine approaches. In the present review, we summarize the current evidence of predictive biomarkers for personalized therapy approaches in the treatment of parenchymal BM.

Exosomes and Brain Metastases: A Review on Their Role and Potential Applications

Brain metastases (BM) are a frequent complication in patients with advanced stages of cancer, associated with impairment of the neurological function, quality of life, prognosis, and survival. BM treatment consists of a combination of the available cancer therapies, such as surgery, radiotherapy, chemotherapy, immunotherapy and targeted therapies. Even so, cancer patients with BM are still linked to poor prognosis, with overall survival being reported as 12 months or less. Intercellular communication has a pivotal role in the development of metastases, therefore, it has been extensively studied not only to better understand the metastization process, but also to further develop new therapeutic strategies. Exosomes have emerged as key players in intercellular communication being potential therapeutic targets, drug delivery systems (DDS) or biomarkers. In this Review, we focus on the role of these extracellular vesicles (EVs) in BM formation and their promising application in the development of new BM therapeutic strategies.

Efficacy and Safety of a Second Course of Stereotactic Radiation Therapy for Locally Recurrent Brain Metastases: A Systematic Review

Simple Summary

Approximately 30% of patients diagnosed with cancer will ultimately develop brain metastases. Many improvements have been made in systemic and local cancer treatments, which have increased overall survival but also, as a consequence, the number of patients who present with local recurrence following intracranial stereotactic radiotherapy. The management of these recurrences remains controversial. The aim of our review is to evaluate the efficacy and tolerance of a second course of stereotactic radiotherapy.

Abstract

Recent advances in cancer treatments have increased overall survival and consequently, local failures (LFs) after stereotactic radiotherapy/radiosurgery (SRS/SRT) have become more frequent. LF following SRS or SRT may be treated with a second course of SRS (SRS2) or SRT (SRT2). However, there is no consensus on whenever to consider reirradiation. A literature search was conducted according to PRISMA guidelines. Analysis included 13 studies: 329 patients (388 metastases) with a SRS2 and 135 patients (161 metastases) with a SRT2. The 1-year local control rate ranged from 46.5% to 88.3%. Factors leading to poorer LC were histology (melanoma) and lack of prior whole-brain radiation therapy, large tumor size and lower dose at SRS2/SRT2, poorer response at first SRS/SRT, poorer performance status, and no controlled extracranial disease. The rate of radionecrosis (RN) ranged from 2% to 36%. Patients who had a large tumor volume, higher dose and higher value of prescription isodose line at SRS2/SRT2, and large overlap between brain volume irradiated at SRS1/SRT1 and SRS2/SRT2 at doses of 18 and 12 Gy had a higher risk of developing RN. Prospective studies involving a larger number of patients are still needed to determine the best management of patients with local recurrence of brain metastases