Assessment of Brain Metastasis at Diagnosis in Non-Small-Cell Lung Cancer: A Prospective Observational Study From North India

Brain metastases from lung cancer: recent advances and novel therapeutic opportunities

Metastatic intracranial progression drastically impacts prognosis, therapeutic considerations and quality of life. The increasing incidence of lung cancer patients developing brain metastases (BM) parallels the incorporation of more effective systemic agents and improved surveillance. Our evolving knowledge of BM pathophysiology, along with advancements in surgical, radiotherapy and systemic therapy options, is rapidly changing prognostication and treatment paradigms. Optimal management of BM in the modern era is patient-specific, dependent on performance status, comorbidities, intracranial and extracranial disease burden, leptomeningeal disease, and the presence of targetable mutations. The purpose of this review is to provide a detailed overview of the detection, prognostication, and multidisciplinary, management of BM arising from non-small cell lung cancer and small cell lung cancer. We discuss contemporary evidence and active clinical trials supporting a wide array of treatment options, including surgery, radiosurgery, memory-avoidance whole brain radiation, craniospinal irradiation, chemotherapy, targeted agents and immunotherapy. Multidisciplinary paradigms will continue to evolve as currently accruing randomized trials evaluating these promising treatments options mature.

Brain Imaging in Patients with Non-Small Cell Lung Cancer-A Systematic Review

Background: Lung cancer frequently metastasizes to the brain, liver, and adrenal glands with a significant negative prognostic impact on overall survival and quality of life (QoL). To optimize treatment and prognosis, adequate staging with the detection of distant metastases is crucial. The incidence of brain metastases in potentially resectable early-stage non-small cell lung cancer (NSCLC) is as low as 3%; hence, the need for preoperative brain imaging has been a constant matter of debate, especially in stage II. In stages III and IV NSCLC, neuroimaging is an essential part of staging. Methods: A systematic literature search was performed. Publications from 1999 to 2024, focusing on preoperative brain imaging (BI) in the staging of stages I-IV NSCLC, were included. Data extraction included study population characteristics, the modality of BI, the incidence of brain metastases (BMs), and the main outcomes of the studies. The final included studies were selected according to the PRISMA criteria. In the second step, guidelines on BI in NSCLC staging of major importance were identified and compared. Results: A total of 530 articles were identified, of which 25 articles were selected. Four prospective studies and 21 retrospective investigations were included. Most of the investigations focused on BI in the early stages. The main imaging modality for BI was magnetic resonance imaging (MRI), followed by computed tomography (CT). Besides the identified 25 studies, the most important internationally applied guidelines on brain imaging in the staging of NSCLC were reviewed. While some guidelines agree on preoperative BI in NSCLC stage III (Union for International Cancer Control-UICC eighth edition) patients, other guidelines recommend earlier BI starting from clinical stage II. All mentioned guidelines homogenously recommend BI in patients with symptoms suggestive of brain pathologies. Conclusions: BI in NSCLC staging is recommended in neurologically symptomatic patients suggestive of brain metastases as well as NSCLC patients with stage III disease. Neuroimaging in stage IA patients, as well as in pure GGO (Ground-Glass Opacity) lesions, was considered unnecessary. The predominantly applied imaging modality was ce-MRI (contrast-enhanced magnetic resonance imaging). Inconsistency exists concerning BI in stage II. The identification of prognostic factors for developing BM in patients with early-stage NSCLC could help to clarify which subgroup might benefit from preoperative BI.

Prognostic value of pre-treatment neutrophil-to-lymphocyte ratio in patients with brain metastasis from cancer: a meta-analysis

Evidence shows that inflammatory responses play an essential role in the development of brain metastases (BM). The goal of this meta-analysis was to critically evaluate the literature regarding the use of the neutrophil to lymphocyte ratio (NLR) to predict the prognosis of patients with BM to help clinicians institute early interventions and improve outcomes. We conducted systematic review and meta-analysis, utilizing data from prominent databases, including PubMed, Cochrane Library and China National Knowledge Infrastructure databases. Our inclusion criteria encompassed studies investigating the studies that assessed the association between NLR and overall survival (OS). We included 11 articles, with 2629 eligible patients, to evaluate the association between NLR and OS. High NLR was significantly associated with shorter OS, with a pooled hazard ratio (HR) of 1.82 (95% CI 1.57-2.11). Subgroup analysis revealed that this association was consistent across different regions, with HRs of 2.03 (95% CI 1.67-2.46) in Asian populations and 1.58 (95% CI 1.35-1.84) in non-Asian populations. Additionally, in a subgroup analysis based on NLR cut-off values, patients with NLR ≥ 3 had an HR of 1.69 (95% CI 1.46-1.96), while those with NLR < 3 had an HR of 2.26 (95% CI 1.64-3.11). Sensitivity analysis confirmed that no single study significantly influenced the pooled effect size. Our meta-analysis confirmed the prognostic value of NLR in patients with brain metastasis.

[Brain metastases]

Cerebral metastases in patients with metastatic lung cancer are found in more than 30% of patients at baseline and manifest themselves in two out of three patients during disease evolution. For a long time, the cerebral manifestation of the disease was classified as prognostically unfavorable and hence such patients were regularly excluded from therapy studies. In the context of targeted molecular therapy strategies and established immuno-oncological systemic therapies, the blood-brain barrier no longer represents an insurmountable barrier. However, the treatment of brain metastases requires decision making in a multidisciplinary team within dedicated lung cancer and/or oncology centers. The differentiated treatment decision is based on the number, size and location of the brain metastases, neurology and general condition, comorbidities, potential life expectancy and the patient's wishes, but also tumor biology including molecular targets, extra-cranial tumor burden and availability of a CNS-effective therapy. Systemic therapies as well as neurosurgical and radiotherapeutic concepts are now often combined for optimized and prognosis-improving therapeutic strategies.

Blood Neurofilament Light Chain and Glial Fibrillary Acidic Protein as Promising Screening Biomarkers for Brain Metastases in Patients with Lung Cancer

The diagnosis of brain metastases (BMs) in patients with lung cancer (LC) predominantly relies on magnetic resonance imaging (MRI), a method that is constrained by high costs and limited accessibility. This study explores the potential of serum neurofilament light chain (sNfL) and serum glial fibrillary acidic protein (sGFAP) as screening biomarkers for BMs in LC patients. We conducted a retrospective analysis of 700 LC cases at the National Cancer Center, Korea, from July 2020 to June 2022, measuring sNfL and sGFAP levels at initial LC diagnosis. The likelihood of BM was evaluated using multivariate analysis and a predictive nomogram. Additionally, we prospectively monitored 177 samples from 46 LC patients initially without BM. Patients with BMs (n= 135) had significantly higher median sNfL (52.5 pg/mL) and sGFAP (239.2 pg/mL) levels compared to those without BMs (n = 565), with medians of 17.8 pg/mL and 141.1 pg/mL, respectively (p < 0.001 for both). The nomogram, incorporating age, sNfL, and sGFAP, predicted BM with an area under the curve (AUC) of 0.877 (95% CI 0.84-0.914), showing 74.8% sensitivity and 83.5% specificity. Over nine months, 93% of samples from patients without BM remained below the cutoff, while all patients developing BMs showed increased levels at detection. A nomogram incorporating age, sNfL, and sGFAP provides a valuable tool for identifying LC patients at high risk for BM, thereby enabling targeted MRI screenings and enhancing diagnostic efficiency.

Clinicopathological characteristics and prognosis of synchronous brain metastases from non-small cell lung cancer compared with metachronous brain metastases

Purpose

Brain metastasis (BM) from non-small cell lung cancer (NSCLC) is a serious complication severely affecting patients' prognoses. We aimed to compare the clinicopathological features and prognosis of synchronous and metachronous BM from NSCLC.

Methods

Clinical data of 461 patients with brain metastases from NSCLC who visited the Cancer Hospital of China Medical University from 2005 to 2017 were retrospectively collected. We analyzed the pathophysiological characteristics of synchronous and metachronous BM from NSCLC and survival rates of the patients. Propensity score matching analysis was used to reduce bias between groups. In addition, we used the Kaplan-Meier method for survival analysis, log-rank test to compare survival rates, and Cox proportional hazards regression model for multivariate prognosis analysis.

Results

Among 461 patients with BM, the number of people who met the inclusion criteria was 400 cases, and after 1:2 propensity score matching,130 had synchronous BM and 260 had metachronous BM. The survival time was longer for metachronous BM in driver mutation-negative patients with squamous cell carcinoma than synchronous BM. Conversely, metachronous and synchronous BM with gene mutations and adenocarcinoma showed no differences in survival time. Multivariate analysis showed that metachronous BM was an independent prognostic factor for overall survival. Furthermore, the pathological type squamous cell carcinoma and Karnofsky Performance Status score <80 were independent risk factors affecting overall survival.

Conclusion

BM status is an independent factor influencing patient outcome. Moreover, synchronous and metachronous BM from NSCLC differ in gene mutation profile, pathological type, and disease progression and hence require different treatments.

Sunvozertinib for patients in China with platinum-pretreated locally advanced or metastatic non-small-cell lung cancer and EGFR exon 20 insertion mutation (WU-KONG6): single-arm, open-label, multicentre, phase 2 trial

BACKGROUND

Sunvozertinib is an oral, irreversible, and selective tyrosine kinase inhibitor that has a favourable safety profile and encouraging antitumour activity, as shown in phase 1 studies of patients with heavily pretreated non-small cell lung cancer (NSCLC) with EGFR exon 20 insertion mutation (exon20ins). We aimed to assess the antitumour efficacy of sunvozertinib in patients with platinum-pretreated locally advanced or metastatic NSCLC with EGFR exon20ins.

METHODS

WU-KONG6 is a single-group, open-label, multicentre phase 2 trial of sunvozertinib monotherapy, conducted across 37 medical centres in China. We enrolled adult patients with pathologically or cytologically confirmed locally advanced or metastatic NSCLC whose tumour tissue carried an EGFR exon20ins mutation. All patients had received at least one line of previous systemic therapy, with at least one line containing platinum-based chemotherapy. The primary endpoint was objective response rate (ORR), as assessed by the independent review committee. The ORR was defined as the percentage of patients who achieved complete or partial response, confirmed by two separate assessments with at least 4-week time interval, until disease progression or initiation of any new anti-cancer therapy. Enrolled patients received sunvozertinib 300 mg once daily until meeting discontinuation criteria per the protocol. Patients who received at least one dose of treatment and were evaluable for efficacy analysis were included in the primary analysis, and all patients who received at least one dose of treatment were included in the safety analysis. This study is registered with ChinaDrugTrials.org, CTR20211009, and ClinicalTrials.gov, NCT05712902, and efficacy and safety follow-up are ongoing.

FINDINGS

Between July 19, 2021, and May 6, 2022, 104 patients were enrolled. At data cutoff (Oct 17, 2022), the last enrolled patient had been followed up for about 6 months. Among 97 patients evaluable for efficacy analysis, 59 (61%) patients achieved tumour response, with a confirmed ORR of 61% (95% CI 50-71). All tumour responses were partial responses. Tumour responses were observed irrespective of age, sex, smoking history, EGFR exon20ins subtypes, brain metastasis at baseline, previous lines of therapy, and history of onco-immunotherapy. In total, 19 death events occurred over a median follow-up period of 7·6 months (IQR 6·1-9·4). Sunvozertinib was well tolerated at 300 mg once daily. The most common grade 3 or worse treatment-related adverse events were blood creatine phosphokinase increased (18 [17%] of 104), diarrhoea (eight [8%]), and anaemia (six [6%]). The most common serious treatment-related adverse events were interstitial lung disease (five [5%] of 104), anaemia (three [3%]), vomiting (two [2%]), nausea (two [2%]) and pneumonia (two [2%]).

INTERPRETATION

In this phase 2 study, sunvozertinib demonstrated antitumour efficacy in patients with platinum-based chemotherapy pretreated NSCLC with EGFR exon20ins, with a manageable safety profile. A multinational randomised, phase 3 study of sunvozertinib versus platinum-doublet chemotherapy in EGFR exon20ins NSCLC is ongoing (NCT05668988).

FUNDING

Dizal Pharmaceutical.

Genomic Alterations and the Incidence of Brain Metastases in Advanced and Metastatic NSCLC: A Systematic Review and Meta-Analysis

INTRODUCTION

Brain metastases (BMs) in patients with advanced and metastatic NSCLC are linked to poor prognosis. Identifying genomic alterations associated with BM development could influence screening and determine targeted treatment. We aimed to establish prevalence and incidence in these groups, stratified by genomic alterations.

METHODS

A systematic review and meta-analysis compliant with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses were conducted (PROSPERO identification CRD42022315915). Articles published in MEDLINE, EMBASE, and Cochrane Library between January 2000 and May 2022 were included. Prevalence at diagnosis and incidence of new BM per year were obtained, including patients with EGFR, ALK, KRAS, and other alterations. Pooled incidence rates were calculated using random effects models.

RESULTS

A total of 64 unique articles were included (24,784 patients with NSCLC with prevalence data from 45 studies and 9058 patients with NSCLC having incidence data from 40 studies). Pooled BM prevalence at diagnosis was 28.6% (45 studies, 95% confidence interval [CI]: 26.1-31.0), and highest in patients that are ALK-positive (34.9%) or with RET-translocations (32.2%). With a median follow-up of 24 months, the per-year incidence of new BM was 0.13 in the wild-type group (14 studies, 95% CI: 0.11-0.16). Incidence was 0.16 in the EGFR group (16 studies, 95% CI: 0.11-0.21), 0.17 in the ALK group (five studies, 95% CI: 0.10-0.27), 0.10 in the KRAS group (four studies, 95% CI: 0.06-0.17), 0.13 in the ROS1 group (three studies, 95% CI: 0.06-0.28), and 0.12 in the RET group (two studies, 95% CI: 0.08-0.17).

CONCLUSIONS

Comprehensive meta-analysis indicates a higher prevalence and incidence of BM in patients with certain targetable genomic alterations. This supports brain imaging at staging and follow-up, and the need for targeted therapies with brain penetrance.

Circulating hsa_circ_0072309, acting via the miR-100/ACKR3 pathway, maybe a potential biomarker for the diagnosis, prognosis, and treatment of brain metastasis from non-small-cell lung cancer

BACKGROUND

One of the main causes of lung cancer-related death is brain metastasis (BM). Finding early indicators of BM derived from lung cancer is crucial. Therefore, this study was designed to determine if serum hsa_circ_0072309 may be employed as a potential biomarker for BM induced by non-small-cell lung cancer (NSCLC) and to understand its possible underlying mechanism.

METHODS

Primary lung cancer and healthy neighboring tissues were obtained from all patients, while BM tissues were taken from BM+ patients. Serum specimens were collected from all patients and healthy volunteers. Hsa_circ_001653, miR-100, and ACKR3 RNA expressions were analyzed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and atypical chemokine receptor 3 (ACKR3) protein expression by western blotting (WB), immunohistochemistry (IHC), and enzyme-linked immunosorbent assay (ELISA). In order to examine the effect of serum hsa_circ_0072309 and its relevant mechanism on BM development, an NSCLC-associated BM model in mice was established.

RESULTS

According to the results, miR-100 expression was down-regulated in primary lung cancer tissues compared to healthy lung tissues in all NSCLC patients, and circ_0072309 and ACKR3 expression were up-regulated. In BM tissues compared with primary lung tumors of BM+ patients, in serum samples from all patients compared to healthy volunteers, and in lung tumors of BM+ patients compared to those from BM- patients. Patients' serum exhibits the same level of hsa_circ_0072309/miR-100/ACKR3 expression as in BM samples. Advanced tumor-node-metastasis (TNM) stage, higher BM, shorter post-operative overall survival (OS), and progression-free survival (PFS) are all substantially associated with increased serum circ_0072309 levels in BM+ patients. In animal models, serum owning hsa_circ_0072309 from BM+ patients facilitates BM formation by regulating the miR-100/ACKR3 pathway.

CONCLUSIONS

The current preliminary research reveals serum hsa_circ_0072309 as a possible biomarker and target for early diagnosis, prognosis, and therapy of NSCLC-derived BM and suggests a substantial role for the hsa_circ_0072309/miR-100/ACKR3 axis in the formation of BM from NSCLC.

Advances in the management of non-small-cell lung cancer harbouring EGFR exon 20 insertion mutations

Epidermal growth factor receptor (EGFR) mutation is one of the key oncogenic mutations in non-small-cell lung cancer with adenocarcinoma histology. Exon 19 deletions and exon 21 L858R substitutions account for 90%, while EGFR exon 20 insertions constitute 4-10% of EGFR mutations and are the third most prevalent activating EGFR mutations. EGFR exon 20 insertions are associated with decreased sensitivity to EGFR tyrosine kinase inhibitors and, until recently, effective targeted therapy against these tumours remained an unmet clinical need and chemotherapy was the only treatment of choice available. The approval of amivantamab and mobocertinib for patients who have progressed after chemotherapy represents an important step forward in the management of these patients. Here in this review, we summarize the epidemiology, structure and the tumour microenvironment of EGFR exon 20 insertion and also review the systemic treatments, including targeted therapies and ongoing clinical trials in EGFR exon 20 insertion mutations, as well as detection methods for EGFR exon 20 insertion. Lastly, resistant mechanisms and future directions are addressed.

Osimertinib for EGFR-Mutant Non-Small-Cell Lung Cancer Central Nervous System Metastases: Current Evidence and Future Perspectives on Therapeutic Strategies

Central nervous system (CNS) metastases are common in non-small-cell lung cancer (NSCLC) and associated with poor prognosis and high disease burden. Effective options are needed to treat CNS metastases, and delay or prevent their formation. For epidermal growth factor receptor mutation-positive (EGFRm) advanced NSCLC and brain metastases, upfront EGFR-tyrosine kinase inhibitors (TKIs) are recommended by the joint European Association of Neuro-Oncology-European Society for Medical Oncology and experts. While early-generation EGFR-TKIs have limited CNS efficacy, the third-generation, irreversible, EGFR-TKI osimertinib has potent efficacy in NSCLC CNS metastases. This review discusses the CNS data of osimertinib in the context of therapeutic strategies and future prospects based on expert review of published literature and relevant clinical, real-world, and ongoing studies in this setting. Osimertinib penetrates the blood-brain barrier and achieves greater exposure in the brain compared with other EGFR-TKIs. Osimertinib has demonstrated CNS efficacy, including in leptomeningeal metastases, in EGFRm advanced disease. In EGFRm stage IB-IIIA NSCLC, adjuvant osimertinib reduced CNS disease recurrence versus placebo. The burden and poor prognosis of CNS metastases necessitate more therapeutic options for their management and reduced risk of recurrence in patients with EGFRm NSCLC. Clinical studies are ongoing in advanced disease to investigate osimertinib combinations with chemotherapy/radiation therapy and optimal treatment post-CNS progression with osimertinib. Further prospective research evaluating treatments using CNS-specific endpoints and evaluating CNS resistance is needed to improve outcomes for patients with CNS metastases.

Real-world risk of brain metastases in stage III non-small cell lung cancer in the era of PET and MRI staging

Objective

The 2-year incidence of brain metastases (BrMs) in stage III non-small lung cell cancer (NSCLC) has been estimated to be around 30%. However, recent clinical trials have demonstrated considerably lower BrMs rates in this patient population. In this study, we aimed to review the real-world incidence, surveillance, and treatment patterns of BrMs in stage III NSCLC.

Materials and methods

Using a retrospective single-center study design, we identified patients with stage III NSCLC who received radiation with curative intent over a 10-year period. Outcome variables included BrMs incidence, overall survival (OS), and survival from date of BrMs. Additionally, we assessed patterns of BrMs surveillance in stage III NSCLC and treatment.

Results

We identified a total of 279 stage III NSCLC patients, of which 160 with adequate records were included in the final analyses [adenocarcinoma (n = 96), squamous cell carcinoma (n = 53), other histology subtype (n = 11)]. The median OS for the entire cohort was 41 months (95% CI, 28-53), while the median time from BrMs to death was 19 months (95% CI, 9-21). Twenty-three patients (14.4%) received planned surveillance brain MRIs at 6, 12, and 24 months after completion of treatment. The remaining 137 patients (85.6%) received brain MRIs at systemic recurrence (restaging) or when neurologically symptomatic. A total of 37 patients (23%) developed BrMs, with a 2-year cumulative BrMs incidence of 17% (95% CI, 11-23). A higher incidence of BrMs was identified in patients with adenocarcinoma relative to those with squamous cell carcinoma (p < 0.01). Similarly, a higher 2-year BrMs incidence was observed in patients who received planned surveillance brain MRI relative to those who did not, although statistical significance was not reached. Stereotactic radiosurgery (SRS) treated 29 of BrMs patients (78.4%) and was preferred over WBRT, which treated only 3 patients (8.1%).

Conclusions

At our center, BrMs incidence in stage III NSCLC patients was lower than historically reported but notably higher than the incidence described in recent clinical trials. Routine BrMs surveillance potentially allows earlier detection of asymptomatic BrMs. However, asymptomatic BrMs were mostly detected on restaging MRI at the time of recurrence.

Principles of Lung Cancer Metastasis to Brain

Lung cancer is a disease associated with significant morbidity and mortality on a global setting. This form of cancer commonly gives raise to metastatic lesions the brain, which can further worsen outcomes. In this focused review, we discuss an overview of lung cancers that metastasize to the brain: known risk factors; means of detection and diagnosis; and options for treatment including a comparison between surgical resection, stereotactic radiosurgery, and whole-brain radiation therapy. These interventions are still being assessed by clinical trials and continue to be modified through evidence-based practice.

Preoperative neutrophil-to-lymphocyte ratio (preNLR) for the assessment of tumor characteristics in lung adenocarcinoma patients with brain metastasis

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A relationship between preoperative Neutrophil-to-Lymphocyte ratio (preNLR) and brain metastasis characteristics such as tumor location and peritumoral brain edema is proposed.

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The corresponding spearman correlations of peritumoral brain edema and preoperative NLR between different tumor location was performed.

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A prognostic nomogram, that provide survival predictions for brain metastasis on lung adenocarcinoma (LUAD) patients has been established.

Objectives

Brain metastases from lung adenocarcinoma cause significant patient mortality. This study aims to evaluate the role of preoperative Neutrophil-to-Lymphocyte ratio (preNLR) in predicting the survival and prognosis of Lung adenocarcinoma (LUAD) patients with brain metastasis (BM) and provide more references for predicting peritumoral edema.

Methods

We retrospectively reviewed 125 LUAD-BM patients who had undergone surgical resection from December 2015 to December 2020. The clinical characteristic, demographic, MRI data, and preNLR within 24–48 h before craniotomy were collected. Patients were divided into two groups based on preNLR (high NLR and low NLR), with cutoff values determined by receiver operating characteristic (ROC) analysis. Association between preoperative NLR and clinical features was determined by using Pearson chi-squared tests. Uni- and multivariate analyzes were performed to compare the overall survival (OS) of clinical features.

Results

The patients were divided into NLR-low (64 patients) and NLR-high (61 patients) groups based on receiver operating characteristic analysis of NLR area. According to correlation analysis, a high preNLR (NLR≥2.8) is associated with the both supra- and infratentorial location involved (P = 0.017) and a greater incidence of severe peritumoral edema (P = 0.038). By multivariable analysis, age ≥ 65 years (P = 0.011), KPS < 70 (P = 0.043), elevated preNLR (P = 0.013), extracerebral metastases (P = 0.003), EGFR/ALK+ (P = 0.037), postoperative radiotherapy (P = 0.017) and targeted therapy (P = 0.007) were independent prognostic factors. OS nomogram was constructed based on cox model and model performance was examined (AUC = 0.935).

Conclusions

PreNLR may serve as a prognosis indicator in LUAD patients with brain metastasis, and high preNLR tends to be positively associate with multiple locations and severe peritumoral edema.

Revisiting Indications for Brain Imaging During the Clinical Staging Evaluation of Lung Cancer

Introduction

Available guidelines are inconsistent as to whether patients with newly diagnosed clinical stage II NSCLC should receive routine brain imaging.

Methods

The National Cancer Database was queried for the prevalence of isolated brain metastases among patients with newly diagnosed NSCLC in 2016 and 2017. Patients with metastases in locations other than the brain were excluded. The prevalences were then stratified by clinical T and N classifications and further stratified into a summary stage, which was calculated based on T and N classifications. The summary stage represents the clinical stage that would have been available at the time of decision for brain imaging.

Results

A total of 6,949 of 149,958 patients (4.6%) with clinical stages I, II, III, or brain-limited stage IV NSCLC had dissemination limited to the brain. As T and N stages increased, prevalence of brain metastases generally increased. Among patients with node-negative (N0) NSCLC, the prevalence of brain-only metastases increased from 1.2% in patients with T1a to 3.8% among patients with T4 (p < 0.001). Among patients with T1a, the prevalence of brain-only metastases increased from 1.2% for patients with N0 to 7.9% for patients with N3 (p < 0.001). The prevalence of brain-limited metastases generally increased with increasing summary stage. The prevalence of brain-only metastases among patients with stage IA was 1.7% whereas that among patients with stage IIIA was 6.7% (p < 0.001). Of note, the prevalence of brain-limited metastases was approximately 6% for both summary stages II and III.

Conclusions

Considering the similarity in prevalence of isolated brain metastases and the potential hazards associated with brain imaging in early stage NSCLC, practitioners may consider a more liberal use of brain imaging when interpreting conflicting guidelines.