BMScope: A scoping review to chart the evolving clinical study landscape in brain and leptomeningeal metastasis.

BACKGROUND: Recent studies have challenged the notion that patients with brain metastasis (BM) or leptomeningeal metastasis (LM) should be excluded from systemic therapy clinical trials. This scoping study summarises the BM/LM clinical studies published between 2010 and 2023. METHODS: MEDLINE, CINAHL, CAB Abstracts, PsycINFO, Cochrane Library, HINARI, International Pharmaceutical Abstracts, PubMed, Scopus, Web of Science, and EMBASE electronic databases were searched on 21 June 2021. An updated search was performed on 21 February 2023. Eligible studies should involve investigation of a therapeutic intervention in solid tumour patients with BM and/or LM and a reported patient outcome. Extracted study-level data, included study type, publication date, geographical location, number of BM/LM patients in study, primary tumour type and type of therapeutic intervention. RESULTS: 4921 unique studies were eligible for analysis. The key finding is that BM/LM clinical research is expanding globally, both observational studies and clinical trials. Despite the shift over time towards a higher proportion of systemic therapy trials, the majority still do not include patients with symptomatic disease and lack reporting of BM/LM specific endpoints. Globally, there has been a trend to more international collaboration in BM/LM clinical studies. CONCLUSIONS: This analysis of the BM/LM literature charts the evolving landscape of studies involving this previously excluded population. Given the increasing clinical research activity, particularly involving late-stage systemic therapy trials, it is imperative that due consideration is given to the intracranial activity of new investigational agents. Wider adoption of standardised reporting of intracranial-specific endpoints will facilitate evaluation of relative intracranial efficacy.

Experience of Gamma Knife radiosurgery for treatment of brain metastases in pregnancy with literature review.

Brain metastases during pregnancy poses complex conundrum in management. Stereotactic radiosurgery (SRS) offers valuable option to clinicians in this scenario. We reviewed and described the safety and effectiveness of Gamma Knife (GK) SRS in treating a solitary cerebellar metastasis in a patient with recurrent breast cancer at 28 weeks of gestation. Following multidisciplinary discussion, she consented for urgent single session GK SRS to the brain metastasis with 2 cycles of 3-weekly paclitaxel chemotherapy prior to planned delivery at term. Prior to the frame-based treatment, a trial run with dosimeters placed on the superior and inferior parts of foam knee support showed radiation exposure of 3.12 mSv and 1.06 mSv respectively. A prescription dose of 16 Gy at the 50% isodose was delivered using 24 isocentres over 39.7' of beam on time. The treatment plan had 98% coverage, 89% selectivity and a gradient index of 2.98. Dosimeters placed near the uterine fundus and suprapubic region (consistent with location of fetal head) during the actual treatment recorded 2.83 mSv and 0.27 mSv, which is lower than the trial dosimeter readings. The patient successfully completed SRS treatment and gave birth to a healthy baby two months later. Follow-up MRI at three months interval showed total resolution of the lesion. GK SRS is known for the lowest extracranial dose compared to other SRS modalities. This report and literature review confirmed that GK is a sharp and effective, yet gentle and safe treatment for pregnant patients with brain metastases.

Patient and physician attitudes towards salvage stereotactic radiosurgery or radiotherapy for brain metastases.

Background: The experience of patients with brain metastases treated with stereotactic radiosurgery (SRS) may shape attitudes towards salvage therapy. Furthermore, physician attitudes towards salvage therapy may differ based on specialty and experience. Our objective is to compare physician attitudes and patient experiences with SRS. Methods: Eligible patients with brain metastases treated with one course of SRS or fractionated stereotactic radiotherapy (FSRT) without whole brain radiotherapy (WBRT) in the definitive or postoperative setting at a single institution were surveyed from 11/2021 to 11/2022 regarding their perspectives on salvage therapy. A separate 11-question multi-disciplinary physician survey was distributed to residents, fellows and attendings at seven additional academic institutions in the US. Chi-square test and Mann-Whitney U test were used to assess differences. Results: A total of 30 patients and 88 physicians were surveyed. Most patients reported being satisfied or very satisfied with initial SRS/FSRT (90%). When given an option between WBRT or SRS for salvage treatment, all patients favored SRS. The physicians consisted of radiation oncologists (69.3%), neurosurgeons (19.3%), medical oncologists (8.0%), and neuro-oncologists (3.4%). Most physicians were confident or very confident in their ability to discuss the risks and benefits of SRS for brain metastases (78.9%), but this was significantly lower if the patient had received prior SRS (56.6%, P<.001). In these cases, there were significant differences in response by medical specialty and confidence level (P<0.05). Conclusions: Patients and physicians view tumor control followed by long-term toxicity as the most important factors for salvage therapy after initial SRS for brain metastases.

Dosimetric comparison of ZAP-X, Gamma Knife, and CyberKnife stereotactic radiosurgery for single brain metastasis.

PURPOSE: To evaluate the dosimetric characteristics of ZAP-X stereotactic radiosurgery (SRS) for single brain metastasis by comparing with two mature SRS platforms. METHODS: Thirteen patients with single brain metastasis treated with CyberKnife (CK) G4 were selected retrospectively. The prescription dose for the planning target volume (PTV) was 18-24 Gy for 1-3 fractions. The PTV volume ranged from 0.44 to 11.52 cc.Treatment plans of thirteen patients were replanned using the ZAP-X plan system and the Gamma Knife (GK) ICON plan system with the same prescription dose and organs at risk (OARs) constraints. The prescription dose of PTV was normalized to 70% for both ZAP-X and CK, while it was 50% for GK. The dosimetric parameters of three groups included the plan characteristics (CI, GI, GSI, beams, MUs, treatment time), PTV (D2, D95, D98, Dmin, Dmean, Coverage), brain tissue (volume of 100%-10% prescription dose irradiation V100%-V10%, Dmean) and other OARs (Dmax, Dmean),all of these were compared and evaluated. All data were read and analyzed with MIM Maestro. One-way ANOVA or a multisample Friedman rank sum test was performed, where p < 0.05 indicated significant differences. RESULTS: The CI of GK was significantly lower than that of ZAP-X and CK. Regarding the mean value, ZAP-X had a lower GI and higher GSI, but there was no significant difference among the three groups. The MUs of ZAP-X were significantly lower than those of CK, and the mean value of the treatment time of ZAP-X was significantly shorter than that of CK. For PTV, the D95, D98, and target coverage of CK were higher, while the mean of Dmin of GK was significantly lower than that of CK and ZAP-X. For brain tissue, ZAP-X showed a smaller volume from V100% to V20%; the statistical results of V60% and V50% showed a difference between ZAP-X and GK, while the V40% and V30% showed a significant difference between ZAP-X and the other two groups; V10% and Dmean indicated that GK was better. Excluding the Dmax of the brainstem, right optic nerve and optic chiasm, the mean value of all other OARs was less than 1 Gy. For the brainstem, GK and ZAP-X had better protection, especially at the maximum dose. CONCLUSION: For the SRS treating single brain metastasis, all three treatment devices, ZAP-X system, CyberKnife G4 system, and GammaKnife system, could meet clinical treatment requirements. The newly platform ZAP-X could provide a high-quality plan equivalent to or even better than CyberKnife and Gamma Knife, with ZAP-X presenting a certain dose advantage, especially with a more conformal dose distribution and better protection for brain tissue. As the ZAP-X systems get continuous improvements and upgrades, they may become a new SRS platform for the treatment of brain metastasis.

Targeting autophagy: a promising approach for the treatment of breast cancer brain metastases.

Patients with breast tumors that metastasize to the brain have limited treatment options and a very poor prognosis. More effective therapeutic strategies are desperately needed for this patient population. Recent evidence demonstrates that brain metastases arising from breast tumors display altered energy production that results in enhanced autophagy. Preclinical studies have shown that genetically or pharmacologically disrupting the autophagy pathway significantly decreases the brain metastatic burden, resulting in improved animal survival and increased sensitivity to lapatinib. These findings pave the way for the development of novel strategies targeting autophagy for breast cancer patients with brain metastatic disease.

Malignant Phyllodes Tumor With Chondroblastic Osteosarcomatous Differentiation: A Case Report.

Malignant phyllodes tumors (MPTs) represent the most pernicious type of intralobular stromal proliferation known as a "fibroepithelial lesion" (FEL). They comprise a small fraction of breast malignancies and can present as either a pure MPT or sometimes include a heterologous component (liposarcoma, chondrosarcoma, osteosarcoma, or rhabdomyosarcoma). Of the fraction of MPTs that include heterologous components, very little about those with chondroblastic osteosarcomatous differentiation has been described in the literature. As such, a characteristic staining profile has yet to be established, even though morphological analysis is the cornerstone of diagnosis. The few reported cases have described a poor prognosis. Therefore, we present a case of MPT with chondroblastic osteosarcomatous differentiation to contribute to the dearth of literature examining this entity.

Development of a scoring system to predict local recurrence in brain metastases following complete resection and observation.

PURPOSE: Postoperative stereotactic radiosurgery to the resection cavity in patients with brain metastases is guideline-recommended therapy. However, Japanese Clinical Oncology Group 0504 study showed that postoperative observation could be a therapeutic option in patients with completed resected brain metastases. We hereby investigated the incidence and risk factors for local recurrence after complete resection without immediate radiotherapy and developed a scoring system for its prediction. METHODS: We included 53 patients with 54 brain metastases, who underwent complete resection between January 2016 and December 2021. We identified risk factors for local recurrence and developed a scoring system to predict it using the extracted risk factors, by assigning one point to each risk factor and calculating the total scores for each patient. We evaluated the correlation between the prognostic score and time to local recurrence. RESULTS: Local recurrence occurred in 37 of 54 tumors (68.5%), with a median follow-up duration of 21.0 months. The median time to local recurrence was 5.1 months. Univariate and multivariate analyses revealed that non-lung adenocarcinoma, infratentorial tumors, and no postoperative systemic therapy were identified as risk factors for local recurrence (non-lung adenocarcinoma, p = 0.035; infratentorial tumors, p = 0.044; and no postoperative systemic therapy, p = 0.0069). A score ≥ 2 showed a median time to local recurrence of 2.1 months, starkly contrasting with 30.8 months for a score ≤ 1 (p = 0.0002). CONCLUSIONS: Non-lung adenocarcinoma, infratentorial tumors, and no postoperative systemic therapy were risk factors for local recurrence. Our scoring system can predict local recurrence, thus potentially aiding treatment decisions.

Computed tomography-based radiomics and clinical-genetic features for brain metastasis prediction in patients with stage III/IV epidermal growth factor receptor-mutant non-small-cell lung cancer.

PURPOSE: To evaluate the value of computed tomography (CT)-based radiomics combined with clinical-genetic features in predicting brain metastasis in patients with stage III/IV epidermal growth factor receptor (EGFR)-mutant non-small-cell lung cancer (NSCLC). METHODS: The study included 147 eligible patients treated at our institution between January 2018 and May 2021. Patients were randomly divided into two cohorts for model training (n = 102) and validation (n = 45). Radiomics features were extracted from the chest CT images before treatment, and a radiomics signature was constructed using the Least Absolute Shrinkage and Selection Operator regression. Kaplan-Meier survival analysis was used to describe the differences in brain metastasis-free survival (BM-FS) risk. A clinical-genetic model was developed using Cox regression analysis. Radiomics, genetic, and combined prediction models were constructed, and their predictive performances were evaluated by the concordance index (C-index). RESULTS: Patients with a low radiomics score had significantly longer BM-FS than those with a high radiomics score in both the training (p < 0.0001) and the validation (p = 0.0016) cohorts. The C-indices of the nomogram, which combined the radiomics signature and N stage, overall stage, third-generation tyrosine kinase inhibitor treatment, and EGFR mutation status, were 0.886 (95% confidence interval [CI] 0.823-0.949) and 0.811 (95% CI 0.719-0.903) in the training and validation cohorts, respectively. The combined model achieved a higher discrimination and clinical utility than the single prediction models. CONCLUSIONS: The combined radiomics-genetic model could be used to predict BM-FS in stage III/IV NSCLC patients with EGFR mutations.

Effect of HER2-low status on brain metastasis-free survival and survival after brain metastasis in patients with breast cancer.

AIMS AND OBJECTIVES: The discovery of novel human epidermal growth factor receptor 2 (HER2)-directed antibody‒drug conjugates has accelerated the identification of the HER2-low subtype. However, the biological significance of low HER2 expression in breast cancer brain metastasis (BCBM) is unclear. METHODS: Patients with HER2-negative BC and brain metastasis were retrospectively screened between February 2012 and November 2023. Brain metastasis-free survival (BMFS) and survival after brain metastasis (SABM) were analyzed according to HER2 expression. RESULTS: A total of 201 female patients, 84 of whom were HER2-low and 117 of whom were HER2-zero, were evaluated. The median BMFS in the entire cohort was 35.6 months (95% CI 29.8-41.4). Although HER2-low patients had numerically longer median BMFS than HER2-zero patients (43.7 m vs. 30.1 m, p = 0.025), multivariate analysis revealed that the difference was not significant (p = 0.167). BMFS between the HER2-low and HER2-zero groups was similar in the hormone receptor (HR)-positive (52.8 m vs. 47.6 m, p = 0.276) and HR-negative (15.3 m vs. 19.7 m, p = 0.930) cohorts. The median SABM in the entire cohort was 6.0 months (95% CI 3.8-8.1). HER2-low and HER2-zero patients had similar median SAMB (5.4 m vs. 6.1 m, p = 0.816). The SABM between the HER2-low and HER2-zero groups was similar in the HR-positive (6.3 m vs. 8.7 m, p = 0.375) and HR-negative (3.3 m vs. 4.2 m, p = 0.783) cohorts. CONCLUSIONS: Low HER2 expression does not affect BMFS or SAMB in brain metastatic breast cancer patients in this real-world population.

Crosstalk between breast cancer-derived microRNAs and brain microenvironmental cells in breast cancer brain metastasis.

Breast cancer is the most frequent malignancy in women, constituting 15.2% of all new cancers diagnosed in the United States. Distant breast cancer metastasis accounts for the majority of breast cancer-related deaths; brain metastasis is the third most common site for metastatic breast cancer but is associated with worst prognosis of approximately eight months of survival. Current treatment options for breast cancer brain metastasis (BCBM) are limited and ineffective. To help identify new and effective therapies for BCBM, it is important to investigate the mechanisms by which breast cancer cells metastasize to the brain and thrive in the brain microenvironment. To this end, studies have reported that primary breast tumor cells can prime brain microenvironmental cells, including, astrocytes and microglia, to promote the formation of BCBM through the release of extracellular vesicle-microRNAs (miRNAs). Breast tumor-derived miRNAs can also promote breast cancer cell invasion through the blood-brain barrier by disrupting the integrity of the brain microvascular endothelial cells. In this review, we summarize current literature on breast cancer-derived BCBM-promoting miRNAs, cover their roles in the complex steps of BCBM particularly their interactions with microenvironmental cells within the brain metastatic niche, and finally discuss their therapeutic applications in the management of BCBM.

Immune checkpoint inhibitors as subsequent treatment in older adults with non-small cell lung cancer and synchronous brain metastases.

Background: Immune checkpoint inhibitors (ICIs) have become the mainstay treatment for non-small cell lung cancer (NSCLC). However, there is a lack of studies assessing ICIs as subsequent treatment in older adults with NSCLC and brain metastasis (BM). This retrospective cohort study compared the real-world survival of older patients with NSCLC and BM at diagnosis [synchronous BM (SBM)] previously treated with chemotherapy receiving ICI versus chemotherapy as subsequent treatment. Methods: Patients with NSCLC and SBM ≥65 years previously treated with chemotherapy were identified using the SEER-Medicare database (2010-2019). Patients receiving new chemotherapy and/or Food and Drug Administration (FDA)-approved ICIs as second/third-line treatment were included, excluding those ever-receiving targeted therapies. Each ICI patient was matched to one chemotherapy patient by time to subsequent treatment (within ±30 days) from diagnosis. Overall survival (OS) time was measured from the start of subsequent treatment to death, censored at disenrollment from Medicare Part A/B, enrollment in Part C, or end of study (December 31, 2019), whichever came first. OS curves were estimated and compared using the Kaplan-Meier (KM) method and log-rank test. Hazard ratio (HR) was estimated using a multivariable-adjusted Cox proportional hazards model. Results: Matched cohorts included 546 patients [273 in each group; median age 71 (range, 65-87) years]. ICI patients were older, more likely non-Hispanic, with squamous cell carcinoma, and liver metastasis compared to chemotherapy. KM estimated better survival in ICI than chemotherapy {median survival: 209 days [95% confidence interval (CI): 160-275] vs. 155 days (95% CI: 135-187); log-rank P<0.001}. ICI was associated with a lower adjusted hazard of death [HR =0.63; 95% CI: 0.52-0.75; P<0.001] compared to subsequent chemotherapy treatment. Conclusions: In this population-based study of older patients with NSCLC and SBM previously treated with chemotherapy, subsequent treatment with ICI was associated with improved survival compared to chemotherapy.

Radiation-Induced Lymphopenia and Its Impact on Survival in Patients with Brain Metastasis.

BACKGROUND: Differences in radiation-induced lymphopenia and prognosis between methods of radiotherapy (RT) for brain metastases remain unclear. METHODS: In this retrospective analysis of patients who underwent whole-brain radiotherapy (WBRT) or stereotactic radiosurgery/radiotherapy (SRS/SRT) for brain metastases, baseline total lymphocyte count (TLC) data were obtained within 2 weeks before RT initiation. Follow-up TLC data were evaluated at 0-2, 2-4, and 4-8 weeks after RT completion. Persistent lymphopenia was defined as <800/µL at any time point. RESULTS: Overall, 138 RT courses in 128 patients were eligible (94 WBRT; 44 SRS/SRT). In the WBRT courses, the median baseline TLC was 1325/µL (IQR: 923-1799). Follow-up TLC decreased significantly to 946/µL (626-1316), 992/µL (675-1291), and 1075/µL (762-1435) (p < 0.001). SRS/SRT courses showed no significant TLC decrease. Multivariate analysis revealed female sex, prior RT, baseline TLC < 800/µL, and WBRT use were significantly associated with persistent lymphopenia. In the WBRT group, overall survival was significantly different between those with and without persistent lymphopenia (median, 2.6 and 6.1 months; p < 0.001). However, there was no significant difference in survival in the SRS/SRT group (p = 0.60). CONCLUSION: This study suggests SRS/SRT might be preferable for lymphocyte preservation in brain metastasis patients.

Mucin-Rich Brain Metastasis May Show the T2-FLAIR Mismatch Sign: A Case Report and Literature Review.

This study describes a unique case of single mucin-rich brain metastasis in a patient with breast cancer, mimicking the T2-fluid attenuation inversion recovery (FLAIR) mismatch sign and masquerading as an isocitrate dehydrogenase-mutant astrocytoma. This case highlights the importance of considering mucin-rich lesions in the differential diagnosis of intracranial tumors exhibiting T2-FLAIR mismatch. Clinicians must recognize the potential convergence in imaging characteristics between these metastases and gliomas to guarantee prompt and accurate patient care.

Performance of amide proton transfer imaging to differentiate true progression from therapy-related changes in gliomas and metastases.

OBJECTIVES: Differentiating true progression or recurrence (TP/TR) from therapy-related changes (TRC) is complex in brain tumours. Amide proton transfer-weighted (APT) imaging is a chemical exchange saturation transfer (CEST) MRI technique that may improve diagnostic accuracy during radiological follow-up. This systematic review and meta-analysis elucidated the level of evidence and details of state-of-the-art imaging for APT-CEST in glioma and brain metastasis surveillance. METHODS: PubMed, EMBASE, Web of Science, and Cochrane Library were systematically searched for original articles about glioma and metastasis patients who received APT-CEST imaging for suspected TP/TR within 2 years after (chemo)radiotherapy completion. Modified Quality Assessment of Diagnostic Accuracy Studies-2 criteria were applied. A meta-analysis was performed to pool results and to compare subgroups. RESULTS: Fifteen studies were included for a narrative synthesis, twelve of which (500 patients) were deemed sufficiently homogeneous for a meta-analysis. Magnetisation transfer ratio asymmetry performed well in gliomas (sensitivity 0.88 [0.82-0.92], specificity 0.84 [0.72-0.91]) but not in metastases (sensitivity 0.64 [0.38-0.84], specificity 0.56 [0.33-0.77]). APT-CEST combined with conventional/advanced MRI rendered 0.92 [0.86-0.96] and 0.88 [0.72-0.95] in gliomas. Tumour type, TR prevalence, sex, and acquisition protocol were sources of significant inter-study heterogeneity in sensitivity (I2 = 62.25%; p < 0.01) and specificity (I2 = 66.31%; p < 0.001). CONCLUSION: A growing body of literature suggests that APT-CEST is a promising technique for improving the discrimination of TP/TR from TRC in gliomas, with limited data on metastases. CLINICAL RELEVANCE STATEMENT: This meta-analysis identified a utility for APT-CEST imaging regarding the non-invasive discrimination of brain tumour progression from therapy-related changes, providing a critical evaluation of sequence parameters and cut-off values, which can be used to improve response assessment and patient outcome. KEY POINTS: Therapy-related changes mimicking progression complicate brain tumour treatment. Amide proton imaging improves the non-invasive discrimination of glioma progression from therapy-related changes. Magnetisation transfer ratio asymmetry measurement seems not to have added value in brain metastases.

Morphological MRI features as prognostic indicators in brain metastases.

BACKGROUND: Stereotactic radiotherapy is the preferred treatment for managing patients with fewer than five brain metastases (BMs). However, some lesions recur after irradiation. The purpose of this study was to identify patients who are at a higher risk of failure, which can help in adjusting treatments and preventing recurrence. METHODS: In this retrospective multicenter study, we analyzed the predictive significance of a set of interpretable morphological features derived from contrast-enhanced (CE) T1-weighted MR images as imaging biomarkers using Kaplan-Meier analysis. The feature sets studied included the total and necrotic volumes, the surface regularity and the CE rim width. Additionally, we evaluated other nonmorphological variables and performed multivariate Cox analysis. RESULTS: A total of 183 lesions in 128 patients were included (median age 61 [31-95], 64 men and 64 women) treated with stereotactic radiotherapy (57% single fraction, 43% fractionated radiotherapy). None of the studied variables measured at diagnosis were found to have prognostic value. However, the total and necrotic volumes and the CE rim width measured at the first follow-up after treatment and the change in volume due to irradiation can be used as imaging biomarkers for recurrence. The optimal classification was achieved by combining the changes in tumor volume before and after treatment with the presence or absence of necrosis (p < < 0.001). CONCLUSION: This study demonstrated the prognostic significance of interpretable morphological features extracted from routine clinical MR images following irradiation in brain metastases, offering valuable insights for personalized treatment strategies.

Consideration of Optimal Evaluation Metrics for Internal Gross Tumor Dose Relevant to Tumor Response in Multi-fraction Stereotactic Radiosurgery of Brain Metastasis.

Introduction In stereotactic radiosurgery (SRS) for brain metastasis (BM), the target dose inhomogeneity remains highly variable among modalities, irradiation techniques, and facilities, which can affect tumor response during and after multi-fraction SRS. Volumetric-modulated arcs (VMAs) can provide a concentrically-layered steep dose increase inside a gross tumor volume (GTV) boundary compared to dynamic conformal arcs. This study was conducted to review the optimal evaluation method for the internal GTV doses relevant to maximal response and local control, specifically to examine the significance of the doses 2 mm and 4 mm inside the GTV boundary in VMA-based SRS. Materials and methods This was a planning study for the clinical scenario of a single BM and targeted 25 GTVs of >0.50 cc, including eight spherical models with diameters of 10-45 mm and 17 clinical BMs (GTV: 0.72-44.33 cc). SRS plans were generated for each GTV using VMA with a 5-mm leaf-width multileaf collimator and the optimization that prioritized the steepness of the dose gradient outside the GTV boundary without any internal dose constraints. The dose prescription and evaluation were based on the GTV D V-0.01 cc, a minimum dose of GTV minus 0.01 cc. Two planning systems were compared for the GTV - 2 mm and GTV - 4 mm structures that were generated by equally reducing 2 mm and 4 mm from the GTV surface. The D eIIVs, a minimum dose of the irradiated isodose volume equivalent to the GTV - 2 mm and GTV - 4 mm, were compared to other common metrics. Results The GTV - 2 mm and GTV - 4 mm volumes differed significantly between the systems. In the spherical GTVs, the irradiated isodose surfaces of GTV D 80% and D 50% corresponded to 0.4-1.6 mm (<2 mm) and 1.0-4.6 mm inside the GTV boundary, respectively. In the 25 GTVs, the GTV - 2 mm coverage with the D eIIV varied from 83.7% to 98.2% (95-98% in 68% of the cases), while the GTV coverage with the GTV - 2 mm D eIIV was 20.2-75.9%. In the 23 GTVs of ≥1.26 cc, the GTV coverage with the GTV - 4 mm D eIIV varied from 1.9% to 55.6% (<50% in 87% of the cases). No significant difference was observed between the GTV D 50% and the GTV - 2 mm D eIIV, while the GTV - 4 mm D eIIV was significantly higher than the GTV D 50%. No significant correlations were observed between the GTV D 50% and the D eIIVs of the GTV - 2 mm and GTV - 4 mm. Conclusions The doses 2 mm and 4 mm inside a GTV have low correlations with the GTV D 50% and may be more relevant to maximal response and local control for SRS of BM. The D eIIV instead of the minimum dose of a fixed % coverage (e.g. D 98%) is suitable for reporting the doses 2 mm and 4 mm inside the GTV boundary in terms of avoiding the over- or under-coverage, with consideration to substantial variability in minus margin addition functions among planning systems. In VMA-based SRS with a steep dose gradient, the doses 2-4 mm inside a GTV decrease significantly as the GTV increases, which can attenuate the excessive dose exposure to the surrounding brain in a large BM due to the GTV shrinkage during multi-fraction SRS.

MicroRNA-522-3p promotes brain metastasis in non-small cell lung cancer by targeting Tensin 1 and modulating blood-brain barrier permeability.

Brain metastases account for more than 50 % of intracranial central nervous system tumors. The blood-brain barrier (BBB) is mainly composed of endothelial cells, which exhibit low endocytosis and high efflux pumps. Although they are connected by continuous tight junctions and serve as a protective insulation, the BBB does not prevent the development of brain metastases from non-small cell lung cancer (NSCLC). Improving understanding on the mechanisms underlying the development of brain metastasis and the differential molecular characteristics relative to the primary tumor are therefore key in the treatment of brain metastases. This study evaluated the differential expression of miR-522-3p in NSCLC and brain metastases using the Gene Expression Omnibus database. NSCLC brain metastasis model was constructed to screen for cell lines that demonstrated high potential for brain metastasis; We also observed differential expression of miRNA-522-3p in the paraffin-embedded specimens of non-small cell lung cancer and brain metastases from our hospital. The molecular biological functions of miRNA-522-3p were verified using 5-ethynyl-2'-deoxyuridine (EdU) proliferation assay and Transwell invasion assays. RNA-seq was employed to identify downstream target proteins, and the dual-luciferase reporter assay confirmed Tensin 1 (TNS1), a protein that links the actin cytoskeleton to the extracellular matrix, as the downstream regulatory target protein. In vitro blood-brain barrier models and co-culture models were constructed to further identify the role of miRNA-522-3p and TNS1; the expression of BBB-related proteins (ZO-1 and OLCN) was also identified. In vivo experiments were performed to verify the effects of miRNA-522-3p on the time and incidence of NSCLC brain metastasis. The results showed significantly high expression in GSE51666; consistent results were obtained in brain metastasis cells and paraffin samples. RNA-seq combined with miRNA target protein prediction demonstrated TNS1 to be directly downstream of miR-522-3p and to be associated with cell proliferation and invasion. By regulating ZO-1 and OCLN expression, mi-522-3p/TNS1 may increase tumor cell penetration through the BBB while decreasing its permeability. In vivo, miR-522-3p was further demonstrated to significantly promote the formation of brain metastases. miR-522-3p/TNS1 can affect BBB permeability and encourage the growth of brain metastases by modifying the BBB TJ proteins. This axis offers new therapeutic targets for the prevention of brain metastasis.

Characterization of the tumor microenvironment in breast cancer brain metastasis.

Objective: The difference in the tumor microenvironment (TME) between primary breast cancer (PBC) and breast cancer brain metastasis (BCBM) is still unknown. Herein, we present the landscape of the TME in PBC and BCBM to better understand the process of BCBM. Methods: The Gene Expression Omnibus (GEO) database was used to obtain suitable PBC and BCBM data. Hub genes that were differentially expressed between the two groups were searched. Gene Ontology (GO) and KEGG were used to define the gene's function. Single-cell data were also analyzed to determine the difference between PBC and BCBM. Results: Two datasets (GSE100534 and GSE125989) were used to search for hub genes, and 79 genes were either upregulated or downregulated between the two groups. Four hub genes (COL1A1, PDGFR, MMP3 and FZD7) were related to prognosis. GO and KEGG analyses showed that extracellular matrix and focal adhesion play major roles in the metastasis process. Another two datasets (GSE176078 and GSE186344) were enrolled for single-cell analysis. Single-cell analysis demonstrated that immune cells (66.6 %) form the main part of PBC, while cancer-associated fibroblasts (CAFs) (21.7 %) are the main component of BCBM. Immune cell proportion analysis showed that CD4+/CD8+ T cells (28.9 % and 14.3 %, respectively) and macrophages(M2) accounted for the majority of cells in PBC and BCBM, respectively. Further analysis of the classification of CAFs showed that apCAFs were significantly higher in PBC. Conclusions: This study presents the landscape of BCBM with hub gene searching and single-cell analysis. Showing the difference in the tumor/immune microenvironment of PBC and BCBM, would be beneficial to explore immunotherapy and targeted therapy for BCBM.

Characteristics of Long-Term Survivors With EGFR-Mutant Metastatic NSCLC.

Introduction: Characteristics of long-term survivors in EGFR-mutant (EGFRm) NSCLC are not fully understood. This retrospective analysis evaluated a multi-institution cohort of patients with EGFRm NSCLC treated in the pre-osimertinib era and sought to describe characteristics of long-term survivors. Methods: Clinical characteristics and outcomes were abstracted from the electronic medical records of patients with EGFRm metastatic NSCLC who started first-line therapy before 2015. Demographics and comutations were compared between greater than or equal to 5-year survivors and less than 5-year survivors. Multivariable Cox proportional hazard and logistic regression models were used to evaluate factors associated with survival and the odds of death within 5 years, respectively. Results: Overall, 133 patients were greater than or equal to 5-year survivors; 127 were less than 5-year survivors. Burden of pathogenic comutations including TP53 and PIK3CA was similar between greater than or equal to 5-year survivors and less than 5-year survivors. Receipt of first-line chemotherapy rather than EGFR tyrosine kinase inhibitor was similar between the groups (22% of <5-y versus 31% of ≥5-y). Baseline brain metastasis and history of smoking were associated with higher odds of death within 5 years (odds ratio = 2.16, p = 0.029 and odds ratio = 1.90, p = 0.046, respectively). Among patients without baseline brain metastases, cumulative incidence of brain metastases at 5 years was 42.3%. Both baseline and post-baseline brain metastasis were associated with worse overall survival compared with no brain metastasis (hazard ratio = 3.26, p < 0.001 and hazard ratio = 4.99, p < 0.001, respectively). Conclusions: Within patients treated for EGFRm metastatic NSCLC before 2015, absence of brain metastasis and nonsmoking status were predictive of 5-year survival. Our findings help to define a subset of patients with EGFRm NSCLC with excellent survival outcomes who may not require intensification of initial therapy.

Performance status improvement and advances in systemic treatment after brain metastases resection: a retrospective single-center cohort study of non-small cell lung cancer patients.

BACKGROUND: Brain metastasis (BrM) is prevalent among patients with NSCLC, and surgical resection of BrM constitutes a promising treatment strategy for local management and histopathological diagnosis, although it is offered for a select group of patients. Limited information exists concerning the improvement in performance status (PS) following BrM resection or the outcomes stratified by subsequent systemic therapy. METHODS: We conducted a retrospective single-center cohort study including NSCLC patients with surgically resected BrM and focused on the improvement in PS and subsequent therapy after BrM resection. RESULTS: 71 patients were included, and the median overall survival was 18.3 months (95% confidence interval [95% CI]: 8.7, not reached). Patients with NSCLC who underwent surgical resection of BrM showed significant improvement in PS (18% and 39% showed ECOG PS of 0-1, before and after BrM resection, respectively [p = 0.006]), and patients with PS improvement were younger than those with PS unimprovement (median, 62 years versus 66 years; p = 0.041). Regarding subsequent systemic therapy after BrM resection, 21 patients (30%) received cytotoxic chemotherapy, 14 patients (20%) received tyrosine kinase inhibitors (TKIs), 3 patients (4%) received immune checkpoint inhibitors (ICIs), and 21 patients (30%) received no subsequent therapy. The survival outcomes of patients stratified by subsequent systemic treatments suggested the tendency that those who received TKI or ICI showed better survival outcomes, although a small number of patients hindered statistical comparisons. CONCLUSIONS: We describe the outcomes of patients with NSCLC who underwent surgical resection of BrM, revealing that younger patients were more likely to anticipate improvement in PS, and patients who received TKI or ICI after BrM resection tended to exhibit a more preferable prognosis.