Hippocampal avoidance whole-brain radiotherapy without memantine in preserving neurocognitive function for brain metastases: a phase II blinded randomized trial

Pharmacological and therapeutic innovation to mitigate radiation-induced cognitive decline (RICD) in brain tumor patients

Radiation therapy is a key treatment modality in both primary and metastatic brain tumors. However, despite its efficacy, it often results in cognitive decline, particularly after whole brain RT (WBRT). Radiation-induced cognitive impairment, which affects memory, attention, and executive function, significantly affects Quality Of Life (QOL) and functional independence. Although white matter necrosis, a hallmark of conventional radiation techniques, has become less common with modern methods, cognitive deficits remain a persistent issue. Neuroinflammation is a key driver of this decline, along with disruptions in hippocampal neurogenesis and damage to regions of the brain. Radiation affects neural stem cells, mature neurons, and glial cells, particularly within the hippocampus, affecting cognition. Recent studies suggest that targeting neuroinflammation and other key Signaling pathways (NMDAR, RAAS, PARP, PPAR, etc.) can reduce cognitive impairment. This review examines the theme of radiation-induced cognitive decline and explores possible interventions to prevent or mitigate these outcomes.

Efficacy of Hippocampal Avoidance Whole Brain Radiotherapy to Preserve the Cognitive Functions among Brain Metastasis Patients: Systematic Review and Meta-analysis

This systematic review and meta-analysis aims to gather credible sources of comprehensive information on the efficacy and radiation dose (maximum and minimum) to the hippocampus and contouring area to prevent cognitive dysfunction by hippocampal avoidance whole brain radiation therapy (HA-WBRT). This comprehensive review was conducted in compliance with PRISMA guidelines. The systematic literature search was performed across four databases including pubmed®, Scopus®, Cochrane Library®, and clinicaltrial.gov.in from inception until December 31, 2023. A total of nine eligible studies were selected encompassing a total of 680 patients with brain metastases who underwent radiation therapy. Notably, radiation exposure to the hippocampal area (3 to 7 mm margin) was avoided during whole-brain radiation therapy (WBRT). The maximum dose delivered to the hippocampus varied between 12.61 Gy and 17 Gy in different studies with minimum doses varying from 5.38 Gy to 10 Gy. HA-WBRT significantly preserves delayed recall compared to WBRT (p = <0.001, P = <0.001, <0.001 and P = 0.048), with an effect size (SMD: -0.57, 95% CI: -1.27, 0.12, P = 0.59, I2 = 0%) favoring HA-WBRT. However, the changes in psychomotor speed, visuospatial abilities, executive function, verbal fluency, and so on were not statistically significant between HA-WBRT and WBRT groups. This review underscores the significant positive impact of HA-WBRT in preventing radiation-induced neurocognitive dysfunction in brain metastatic patients, particularly in delayed recall. However, comprehensive cognitive preservation necessitates additional interventions alongside HA-WBRT.

Stereotactic radiosurgery for patients with brain metastases: current principles, expanding indications and opportunities for multidisciplinary care

The management of brain metastases is challenging and should ideally be coordinated through a multidisciplinary approach. Stereotactic radiosurgery (SRS) has been the cornerstone of management for most patients with oligometastatic central nervous system involvement (one to four brain metastases), and several technological and therapeutic advances over the past decade have broadened the indications for SRS to include polymetastatic central nervous system involvement (>4 brain metastases), preoperative application and fractionated SRS, as well as combinatorial approaches with targeted therapy and immune-checkpoint inhibitors. For example, improved imaging and frameless head-immobilization technologies have facilitated fractionated SRS for large brain metastases or postsurgical cavities, or lesions in proximity to organs at risk. However, these opportunities come with new challenges and questions, including the implications of tumour histology as well as the role and sequencing of concurrent systemic treatments. In this Review, we discuss these advances and associated challenges in the context of ongoing clinical trials, with insights from a global group of experts, including recommendations for current clinical practice and future investigations. The updates provided herein are meaningful for all practitioners in clinical oncology.

Preclinical monitoring of radiation-induced brain injury via GluCEST MRI and resting-state fMRI at 7 T: an exploratory study on MRI-guided OAR avoidance

PURPOSE

To assess the value of glutamate chemical exchange saturation transfer (GluCEST) after whole-brain radiotherapy (WBRT) as an imaging marker of radiation-induced brain injury (RBI) and to preliminarily show the feasibility of multiparametric MRI-guided organ at risk (OAR) avoidance.

METHODS

Rats were divided into two groups: the control (CTRL) group (n = 9) and the RBI group (n = 9). The rats in the RBI group were irradiated with an X‑ray radiator and then subjected to a water maze experiment 4 weeks later. In combination with high-performance liquid chromatography (HPLC), we evaluated the value of GluCEST applied to glutamate changes for RBI and investigated the effect of such changes on glutamatergic neuronal function.

RESULTS

The average GluCEST values were markedly lower in the hippocampus and cerebral cortex. Positive correlations were observed between GluCEST values and regional homogeneity (ReHo) values in both the hippocampus and the cerebral cortex. HPLC showed a positive correlation with GluCEST values in the hippocampus. GluCEST values were positively correlated with spatial memory.

CONCLUSION

GluCEST MRI provides a visual assessment of glutamate changes in RBI rats for monitoring OAR cognitive toxicity reactions and may be used as a biomarker of OAR avoidance as well as metabolism to facilitate monitoring and intervention in radiation damage that occurs after radiotherapy.

Trajectory of long-term neuropsychological performances and cognitive-deterioration-free survival after hippocampus-sparing whole-brain radiotherapy in cancer patients mostly with newly diagnosed brain oligometastases

Neurocognitive functions (NCFs) might change after conventional whole-brain radiotherapy (WBRT). The technique of hippocampus sparing during WBRT (HS-WBRT) may substantially preserve NCFs. Therefore, the aim of this study was to examine whether trajectories of neuropsychological performances maintained or improved after HS-WBRT. A total of 125 cancer patients underwent the HS-WBRT course. Before HS-WBRT, all participants underwent multidomain neurocognitive assessment, mainly involving executive functions and hippocampus-related memory. After radiotherapy, the above assessment was administered at regular time points to monitor longitudinal neuropsychological performances. The delta values of post-radiotherapy and baseline NCF scores showed a sustained trend, signifying cognitive maintenance rather than deterioration. This trend was observed for hippocampus-related verbal memory and frontal-lobe-related executive functions, represented by the score of Word List-immediate memory and Modified Card Sorting Test - Complete Categories, respectively. The potential predictors of longitudinal multidomain neuropsychological performances included age at enrollment, baseline NCF scores, and the assessment time (months) elapsed since enrollment, signifying the trajectory of patients' neuropsychological performances after HS-WBRT. Among longitudinal neuropsychological outcomes, there was a considerable time trend toward maintenance in verbal learning immediate memory [odds ratio, 1.112, 95% confidence interval, 1.08 - 1.15], which persisted even after adjusting for the most independent predictor (baseline NCF scores). Functional preservation of longitudinal multidomain neuropsychological performances was evident after HS-WBRT. Such neurocognitive preservation, particularly hippocampus-related memory functions, was meaningfully sustained in our patients after undergoing the standardized course of hippocampus sparing during WBRT.

Hyperbaric oxygen therapy attenuates brain radiation-induced cognitive deficits in rats

Effective therapies for cognitive impairments induced by brain irradiation are currently lacking. This study investigated the therapeutic potential of hyperbaric oxygen therapy (HBOT) for radiation-induced brain injury in a randomized controlled experimental model using adult male Wistar rats. Adult male Wistar rats were divided into four experimental groups: 0 Gy whole brain radiotherapy (WBRT) with normal baric air (NBA) treatment, 0 Gy WBRT with HBOT, 10 Gy WBRT with NBA, and 10 Gy WBRT with HBOT. Behavioral tests and histochemical analyses were conducted four weeks post-WBRT to assess cognitive function, hippocampal microgliosis, apoptosis, and lipid peroxidation. Compared with the rats with 0 Gy WBRT on 28 days, the rats with 10 Gy WBRT on 28 days had significantly higher severity of spatial learning and memory dysfunction and hippocampal microgliosis, newborn neuronal apoptosis, and lipid peroxidation. HBOT significantly prevented and reversed WBRT-induced cognitive deficits, hippocampal microgliosis, newborn neuronal apoptosis, and lipid peroxidation. In addition, HBOT prevented and reversed the increased apoptosis among newborn neural stem cells and neuroblasts caused by 10 Gy WBRT on 7 days. The findings suggest that WBRT disrupts neurogenesis and enhance microgliosis, apoptosis of neuronal progenitors, and lipid peroxidation in the dentate gyrus, potentially leading to cognitive deficits and neuronal death. HBOT may offer a protective effect against these cognitive impairments and their underlying mechanisms in adult male rats following WBRT.

Efficacy and safety evaluation of combined therapies incorporating whole-brain radiotherapy in patients with brain metastases: a systematic review and meta-analysis

BACKGROUND

Whole-brain radiotherapy (WBRT) is a standard and effective approach for brain metastases, but it is linked to neurocognitive complications, specifically issues related to the hippocampus. Innovative strategies are being explored to enhance outcomes. However, a consensus is yet to be reached in this field. Our aim is to investigate the efficacy and safety of WBRT combined with simultaneous integrated boost (SIB), memantine, and hippocampal avoidance (HA) techniques in treatment of brain metastases.

METHODS

In this systematic review and meta-analysis, we comprehensively searched PubMed, MEDLINE, Embase, and Cochrane for studies reporting the efficacy and toxicity of WBRT-based combination therapies from inception to September 19, 2023. Data were pooled using random-effects models. Results were reported as risk ratios (RRs) and risk differences (RDs) for dichotomous outcomes, along with their 95% confidence intervals (CIs). Heterogeneity was evaluated using the I2 statistic.

RESULTS

Among 2175 articles, 29 studies involving 3460 patients were included. The meta-analysis revealed that compared to WBRT alone, combination therapies significantly mitigated neurocognitive function decline (RD = -0.09, 95% CI [-0.18-0.01]; P = 0.03) and intracranial control failure (RR = 0.86, 95% CI [0.52-1.44]; P = 0.02), without increasing the risk of hippocampal recurrence or high-grade toxicities. Notably, HA-WBRT + SIB/memantine demonstrated improved neurocognitive outcomes and survival benefits.

CONCLUSION

WBRT-based combination therapies demonstrate improved efficacy and comparable safety to WBRT alone, with specific emphasis on the effectiveness of HA-WBRT + Memantine and HA-WBRT + SIB in optimizing therapeutic outcomes for brain metastases.

Advances in the Management of Lung Cancer Brain Metastases

Lung cancer, both non-small cell and small cell, harbors a high propensity for spreading to the central nervous system. Radiation therapy remains the backbone of the management of brain metastases. Recent advances in stereotactic radiosurgery have expanded its indications and ongoing studies seek to elucidate optimal fractionation and coordination with systemic therapies, especially targeted inhibitors with intracranial efficacy. Efforts in whole-brain radiotherapy aim to preserve neurocognition and to investigate the need for prophylactic cranial irradiation. As novel combinatorial strategies are tested and prognostic/predictive biomarkers are identified and tested, the management of brain metastases in lung cancer will become increasingly personalized to optimally balance intracranial efficacy with preserving neurocognitive function and patient values.

A Randomised Phase II Trial of Hippocampal Sparing Versus Conventional Whole Brain Radiotherapy After Surgical Resection or Radiosurgery in Favourable Prognosis Patients With 1-10 Brain Metastases

AIMS

To assess in patients with 1-10 brain metastases, each of which has been treated by neurosurgery or stereotactic radiosurgery, whether hippocampal sparing whole brain radiotherapy (HS-WBRT) better spares neurocognitive function (NCF) than standard WBRT. Further, to assess whether a phase III randomised trial of HS-WBRT would be feasible in the UK.

MATERIALS AND METHODS

A multicentre, randomised, open label phase II trial was undertaken, randomising patients to 30Gy in 10 fractions of WBRT or HS-WBRT. The primary endpoint was decline in Total recall using Hopkins Verbal Learning Test Revised (HVLT-R) at 4 months post treatment. To assess this, we aimed to recruit 84 patients over 3 years. Secondary endpoints included further measures of NCF, quality of life, duration of functional independence, local control of treated metastases, development of new metastases, disease control within the hippocampal regions, overall survival, steroid and antiepileptic medication requirements, and toxicity.

RESULTS

The trial closed prematurely due to slower than anticipated recruitment. From April 2016 to January 2018, 23 patients were randomised. Follow up was a median of 25 months. Fifteen patients (6 WBRT, 9 HS-WBRT) were assessed for the primary endpoint; of these, 1 in each arm experienced significant decline in the 4-month HVLT-R Total recall score (p = 0.8). Patients in the HS-WBRT arm experienced less insomnia (p < 0.01) and drowsiness (p < 0.01). There were no differences in other secondary endpoints.

CONCLUSION

A phase III randomised trial of HS-WBRT was shown not to be feasible at this time in the UK. As most randomised trials of HS-WBRT reported to date share common endpoints, including NCF, an individual patient data meta-analysis should be undertaken.

Incidence of hippocampal and perihippocampal brain metastases and impact on hippocampal-avoiding radiotherapy: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

In patients requiring prophylactic cranial irradiation (PCI) or whole-brain radiotherapy (WBRT) for brain metastases (BMs), hippocampal avoidance (HA) has been shown to preserve neurocognitive function and quality of life. Here, we aim to estimate the incidence of hippocampal and perihippocampal BMs and the subsequent risk of local undertreatment in patients undergoing hippocampal sparing radiotherapy.

MATERIALS AND METHODS

MEDLINE, Embase, and Scopus were searched with the terms "Hippocampus", "Brain Neoplasms", and related terms. Trials reporting on the incidence of hippocampal and/or perihippocampal BMs or hippocampal failure rate after PCI or WBRT were included.

RESULTS

Forty records were included, encompassing a total of 5,374 patients with over 32,570 BMs. Most trials employed a 5 mm margin to define the HA zone. In trials reporting on BM incidence, 4.4 % (range 0 - 27 %) and 9.2 % (3 - 41 %) of patients had hippocampal and perihippocampal BMs, respectively. The most common risk factor for hippocampal BMs was the total number of BMs. The reported failure rate within the HA zone after HA-PCI or HA-WBRT was 4.5 % (0 - 13 %), salvageable with radiosurgery in most cases. SCLC histology was not associated with a higher risk of hippocampal failure (OR = 2.49; p = 0.23). In trials comparing with a conventional (non-HA) PCI or WBRT group, HA did not increase the hippocampal failure rate (OR = 1.90; p = 0.17).

CONCLUSION

The overall incidence of hippocampal and perihippocampal BMs is considerably low, with a subsequent low risk of local undertreatment following HA-PCI or HA-WBRT. In patients without involvement, the hippocampus should be spared to preserve neurocognitive function and quality of life.

Perihippocampal failure after hippocampal-avoidance brain radiotherapy in small cell lung cancer patients: Cases report and literature review

RATIONALE

Brain metastasis is a major concern, and may occur in roughly 50% of patients during the clinical course of small cell lung cancer (SCLC). Because prophylactic cranial irradiation reduces the incidence of brain metastases and improves overall survival, prophylactic cranial irradiation is recommended for SCLC patients without distant metastases or an extensive stage and have responded well to systemic therapy. Hippocampal-avoidance whole-brain radiotherapy (HA-WBRT) is preferred to preserve hippocampal function while minimizing negative cognitive effects.

PATIENT CONCERNS

Reducing the dose delivered to the hippocampus below the therapeutic brain dose may increase the risk of hippocampal progression; thus, HA-WBRT may be associated with a risk of perihippocampal recurrence.

DIAGNOSIS

Three patients with SCLC received HA-WBRT and developed intracranial failure during clinical follow-up; 3 relapsed with intracranial failure in the perihippocampal region after 12, 13, and 7 months, respectively.

INTERVENTION AND OUTCOMES

Compared to the therapeutic brain dose of cases and the underdose region around the HA region, we matched MRI scans of intracranial failure and previous planning scans of simulation and found a deviation of the underdosed region within the perihippocampal failure of approximately 55% to 63%.

LESSONS

Perihippocampal failure is a rare clinical outcome in SCLC patients following HA-WBRT. Perihippocampal failure could be caused by an underdose of radiation or by the aggressiveness of the cancer itself. More research into this topic is encouraged.

New Frontiers in the Treatment of Patients with HER2+ Cancer and Brain Metastases: Is Radiotherapy Always Useful?

Brain metastases (BM) pose a significant challenge in the management of HER2+ breast cancer since almost 50% of patients with HER2+ breast cancer develop brain tumors. The complex process of brain metastases involves genetic mutations, adaptations and mechanisms to overcome the blood-brain barrier. While radiotherapy is still fundamental in local therapy, its use is associated with cognitive adverse effects and limited long-term control, necessitating the exploration of alternative treatments. Targeted therapies, including tyrosine kinase inhibitors, monoclonal antibodies, and antibody-drug conjugates, offer promising options for HER2+ breast cancer patients with BM. Clinical trials have demonstrated the efficacy of these agents in controlling tumor growth and improving patient outcomes, posing the question of whether radiotherapy is always the unique choice in treating this cancer. Ongoing research into novel anti-HER2 antibodies and innovative combination therapies holds promise for advancing treatment outcomes and enhancing patient care in this clinical scenario. This narrative review provides a comprehensive overview of traditional medical treatments, molecularly targeted therapy and investigational agents in the management of HER2+ breast cancer with BM, highlighting the evolving landscape and potential future directions in treatment strategies to improve patient survival and quality of life.

Evaluating the sensitivity of EQ-5D-5L in patients with brain metastases: a secondary analysis of NRG CC001

BACKGROUND

EuroQoL EQ-5D-5L is a commonly used measure of health-related quality of life in clinical trials given the use of its index score as a measure of health utilities. It is unclear whether EQ-5D-5L is sensitive to changes in neurocognitive function and progression that occur following brain radiation. This study sought to evaluate the sensitivity of EQ-5D-5L in reflecting these changes.

METHODS

A secondary analysis of NRG Oncology CC001 was performed. Mean EQ-5D-5L index and visual analog scale (VAS) score changes from baseline between groups of patients stratified by neurocognitive function and intracranial progression status were assessed. MD Anderson Symptom Inventory for brain tumor (MDASI-BT) symptom and interference items were also analyzed between groups.

RESULTS

EQ-5D-5L mean index and VAS score changes between patients who had cognitive failure and those who had preserved cognition showed no statistically significant differences at any timepoint. In contrast, VAS changes at 4 months (1.61 vs -5.13, P = .05) and 6 months (8.17 vs -0.14, P = .04) were significantly improved in the patients who survived without intracranial progression. MDASI-BT cognitive factor scores were improved in the cohort of patients with preserved neurocognitive function at 2 months (1.68 vs 2.08, P = .05) and 4 months (1.35 vs 1.83, P = .04). MDASI-BT symptom interference was significantly associated with intracranial progression at 4 months, but not with neurocognitive status.

CONCLUSION

EQ-5D-5L index and VAS scores were not sensitive to neurocognitive changes that patients experienced, but VAS scores were sensitive to progression. This study challenges the routine use of EQ-5D as a quality of life metric in brain metastases clinical trials that are focused on preventing neurocognitive dysfunction.

TRIAL REGISTRATION

NCT# 02360215.

Evaluating the heterogeneity of hippocampal avoidant whole brain radiotherapy treatment effect: A secondary analysis of NRG CC001

BACKGROUND

Hippocampal avoidant whole brain radiotherapy (HA-WBRT) is the standard of care for patients needing WBRT for brain metastases. This study, using existing data from NRG Oncology CC001 including baseline tumor characteristics and patient-reported MD Anderson Symptom Inventory-Brain Tumor (MDASI-BT) scores, sought to identify subgroups of patients that demonstrate differential neuroprotective treatment response to HA-WBRT.

METHODS

An exploratory analysis of NRG CC001, a phase 3 trial in which 518 patients were randomly assigned to WBRT plus memantine or HA-WBRT plus memantine, was performed. Rates of neurocognitive function failure (NCFF) were estimated between subgroups and stratified by arm. Covariate and subgroup interaction with differential treatment response were calculated.

RESULTS

The benefit of HA-WBRT on decreasing NCFF was seen in patients living ≥ 4 months (HR 0.75, 95% CI: 0.58-0.97, P = .03), whereas patients living < 4 months derived no significant neurocognitive benefit. A significant association between baseline MDASI-BT cognitive factor and treatment response (interaction P = .03) was identified. Patients with lower MDASI-BT scores (less patient-reported cognitive impairment) derived significantly greater benefit (HR = 0.64, 95% CI: 0.48-0.85, P = .002) compared to those with highest MDASI-BT scores (HR = 1.24, 95% CI: 0.76-2.04, P = .39). Tumor histology also had a significant interaction (P = .01) with treatment response. Primary lung histology patients derived cognitive failure risk reduction (HR = 0.58, 95% CI: 0.43-0.77, P = .0007) from HA-WBRT, in contrast to nonlung primary histology patients (HR = 1.15, 95% CI: 0.78-1.50, P = .48).

CONCLUSIONS

Differential neuroprotective response to HA-WBRT was identified in this analysis. Patients surviving ≥ 4 months derived benefit from HA-WBRT. There is evidence of heterogeneity of treatment effect for patients with less severe patient-reported cognitive impairment at baseline and those with primary lung histology.

Comparison of conventional and hippocampus-sparing radiotherapy in nasopharyngeal carcinoma: In silico study and systematic review

Background and purpose

Radiation-induced damage to the hippocampi can cause cognitive decline. International recommendations for nasopharyngeal cancer (NPC) radiotherapy (RT) lack specific guidelines for protecting the hippocampi. Our study evaluates if hippocampi-sparing (HS) RT in NPC ensures target coverage and meets recommended dose limits for other at-risk organs.

Materials and methods

In a systematic literature review, we compared hippocampal D40% in conventional and HS RT plans. In an in silico dosimetric study, conventional and HS-VMAT plans were created for each patient, following international recommendations for OAR delineation, dose prioritization and acceptance criteria. We assessed the impact on neurocognitive function using a previously published normal tissue complication probability (NTCP) model.

Results

In four previous studies (n = 79), researchers reduced D40% hippocampal radiation doses in HS plans compared to conventional RT on average from 24.9 Gy to 12.6 Gy.Among 12 NPC patients included in this in silico study, statistically significant differences between HS and conventional VMAT plans were observed in hippocampal EQD2 Dmax (23.8 vs. 46.4 Gy), Dmin (3.8 vs. 4.6 Gy), Dmean (8.1 vs. 15.1 Gy), and D40% (8.3 vs. 15.8 Gy). PTV coverage and OAR doses were similar, with less homogeneous PTV coverage in HS plans (p = 0.038). This translated to a lower probability of memory decline in HS plans (interquartile range 15.8-29.6 %) compared to conventional plans (33.8-81.1 %) based on the NTCP model (p = 0.002).

Conclusion

Sparing the hippocampus in NPC RT is safe and feasible. Given the life expectancy of many NPC patients, their cognitive well-being must be paramount in radiotherapy planning.

DEGRO guideline for personalized radiotherapy of brain metastases and leptomeningeal carcinomatosis in patients with breast cancer

PURPOSE

The aim of this review was to evaluate the existing evidence for radiotherapy for brain metastases in breast cancer patients and provide recommendations for the use of radiotherapy for brain metastases and leptomeningeal carcinomatosis.

MATERIALS AND METHODS

For the current review, a PubMed search was conducted including articles from 01/1985 to 05/2023. The search was performed using the following terms: (brain metastases OR leptomeningeal carcinomatosis) AND (breast cancer OR breast) AND (radiotherapy OR ablative radiotherapy OR radiosurgery OR stereotactic OR radiation).

CONCLUSION AND RECOMMENDATIONS

Despite the fact that the biological subtype of breast cancer influences both the occurrence and relapse patterns of breast cancer brain metastases (BCBM), for most scenarios, no specific recommendations regarding radiotherapy can be made based on the existing evidence. For a limited number of BCBM (1-4), stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (SRT) is generally recommended irrespective of molecular subtype and concurrent/planned systemic therapy. In patients with 5-10 oligo-brain metastases, these techniques can also be conditionally recommended. For multiple, especially symptomatic BCBM, whole-brain radiotherapy (WBRT), if possible with hippocampal sparing, is recommended. In cases of multiple asymptomatic BCBM (≥ 5), if SRS/SRT is not feasible or in disseminated brain metastases (> 10), postponing WBRT with early reassessment and reevaluation of local treatment options (8-12 weeks) may be discussed if a HER2/Neu-targeting systemic therapy with significant response rates in the central nervous system (CNS) is being used. In symptomatic leptomeningeal carcinomatosis, local radiotherapy (WBRT or local spinal irradiation) should be performed in addition to systemic therapy. In patients with disseminated leptomeningeal carcinomatosis in good clinical condition and with only limited or stable extra-CNS disease, craniospinal irradiation (CSI) may be considered. Data regarding the toxicity of combining systemic therapies with cranial and spinal radiotherapy are sparse. Therefore, no clear recommendations can be given, and each case should be discussed individually in an interdisciplinary setting.

Why does HER2-positive breast cancer metastasize to the brain and what can we do about it?

Breast cancer is the most frequent malignancy in women. However, in the middle and late stages, some people develop distant metastases, which considerably lower the quality of life and life expectancy. The brain is one of the sites where metastasis frequently happens. According to epidemiological research, brain metastases occur at a late stage in 30-50% of patients with HER2-positive breast cancer, resulting in a poor prognosis. Additionally, few treatments are available for HER2-positive brain metastatic breast cancer, and the mortality rate is remarkable owing to the complexity of the brain's anatomical structure and physiological function. In this review, we described the stages of the brain metastasis of breast cancer, the relationship between the microenvironment and metastatic cancer cells, and the unique molecular and cellular mechanisms. It involves cancer cells migrating, invading, and adhering to the brain; penetrating the blood-brain barrier; interacting with brain cells; and activating signal pathways once inside the brain. Finally, we reviewed current clinically used treatment approaches for brain metastasis in HER2-positive breast cancer; summarized the traditional treatment, targeted treatment, immunotherapy, and other treatment modalities; compared the benefits and drawbacks of each approach; discussed treatment challenges; and emphasized the importance of identifying potential targets to improve patient survival rates and comprehend brain metastasis in breast cancer.

Hippocampal region avoidance in whole brain radiotherapy in brain metastases: For all or for some? A real-world feasibility report

PURPOSE

Hippocampal sparing whole-brain radiotherapy (HS-WBRT) showed significantly lower long-term side effects compared to standard WBRT. Aim of this study is to describe a HS-WBRT real-world monoinstitutional experience within a retrospective cohort.

METHODS

Patients who completed HS-WBRT course, with Karnofsky Performance Status ⩾ 60 and radiological diagnosis of brain metastases (BMs) were enrolled. Treatment was performed using helical Tomotherapy scheduled in 30 Gy in 10 or 12 fractions or 25 Gy in 10 fractions. Oncological outcomes were clinically and radiologically assessed every three months. Toxicity was graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events 4.3.

RESULTS

One hundred and nineteen patients from 2016 to 2020 met inclusion criteria; after a median follow-up of 18 months, 29 patients were alive; 6- and 12-months overall survival rates were 66% and 41%, respectively. HS-WBRT response was assessed for 72 patients. Median time to any progression and intracranial failure (IF) was 4.5 and 13.7 months, respectively. The 6- and 12-month IF rates were 85% and 57%. Among 40 patients (34%) who experienced IF, 17 (42%) were oligometastatic, 23 (58%) polymetastatic and 15/40 developed IF within the hippocampi avoidance zone. No grade (G) ⩾ 2 acute toxicities were reported and one G2 (dizziness) late toxicity was described.

CONCLUSIONS

HS-WBRT is well tolerated, and despite the hippocampal sparing region, the oncological control is satisfying. Further investigation is warranted to find patients who could most benefit from a HS-WBRT approach.

Mitigating radiation-induced cognitive toxicity in brain metastases: More questions than answers

The emergence of advanced systemic therapies added to the use of cranial radiation techniques has significantly improved outcomes for cancer patients with multiple brain metastases (BM), leading to a considerable increase in long-term survivors. In this context, the rise of radiation-induced cognitive toxicity (RICT) has become increasingly relevant. In this critical narrative review, we address the controversies arising from clinical trials aimed at mitigating RICT. We thoroughly examine interventions such as memantine, hippocampal avoidance irradiation during BM treatment or in a prophylactic setting, and the assessment of cognitive safety in stereotactic radiosurgery (SRS). Our focus extends to recent neuroscience research findings, emphasizing the importance of preserving not only the hippocampal cortex but also other cortical regions involved in neural dynamic networks and their intricate role in encoding new memories. Despite treatment advancements, effectively managing patients with multiple BM and determining the optimal timing and integration of radiation and systemic treatments remain areas requiring further elucidation. Future trials are required to delineate optimal indications and ensure SRS safety. Additionally, the impact of new systemic therapies and the potential effects of delaying irradiation on cognitive functioning also need to be addressed. Inclusive trial designs, encompassing patients with multiple BM and accounting for diverse treatment scenarios, are essential for advancing effective strategies in managing RICT and the treatment of BM patients.

Focused ultrasound combined with radiotherapy for malignant brain tumor: a preclinical and clinical study

INTRODUCTION

Blood-brain barrier (BBB) remains to be the major obstacle to conquer in treating patients with malignant brain tumors. Radiation therapy (RT), despite being the mainstay adjuvant modality regardless of BBB, the effect of radiation induced cell death is hindered by the hypoxic microenvironment. Focused ultrasound (FUS) combined with systemic microbubbles has been shown not only to open BBB but also potentially increased regional perfusion. However, no clinical study has investigated the combination of RT with FUS-BBB opening (RT-FUS).

METHODS

We aimed to provide preclinical evidence of RT-FUS combination in GBM animal model, and to report an interim analysis of an ongoing single arm, prospective, pilot study (NCT01628406) of combining RT-FUS for recurrent malignant high grade glioma patients, of whom re-RT was considered for disease control. In both preclinical and clinical studies, FUS-BBB opening was conducted within 2 h before RT. Treatment responses were evaluated by objective response rate (ORR) using magnetic resonance imaging, progression free survival, and overall survival, and adverse events (AE) in clinical study. Survival analysis was performed in preclinical study and descriptive analysis was performed in clinical study.

RESULTS

In mouse GBM model, the survival analysis showed RT-FUS (2 Gy) group was significantly longer than RT (2 Gy) group and control, but not RT (5 Gy) group. In the pilot clinical trial, an interim analysis of six recurrent malignant high grade glioma patients underwent a total of 24 RT-FUS treatments was presented. Three patients had rapid disease progression at a mean of 33 days after RT-FUS, while another three patients had at least stable disease (mean 323 days) after RT-FUS with or without salvage chemotherapy or target therapy. One patient had partial response after RT-FUS, making the ORR of 16.7%. There was no FUS-related AEs, but one (16.7%) re-RT-related grade three radiation necrosis.

CONCLUSION

Reirradiation is becoming an option after disease recurrence for both primary and secondary malignant brain tumors since systemic therapy significantly prolongs survival in cancer patients. The mechanism behind the synergistic effect of RT-FUS in preclinical model needs further study. The clinical evidence from the interim analysis of an ongoing clinical trial (NCT01628406) showed a combination of RT-FUS was safe (no FUS-related adverse effect). A comprehensive analysis of radiation dosimetry and FUS energy distribution is expected after completing the final recruitment.

Hippocampal avoidance in whole brain radiotherapy and prophylactic cranial irradiation: a systematic review and meta-analysis

PURPOSE

We systematically reviewed the current landscape of hippocampal-avoidance radiotherapy, focusing specifically on rates of hippocampal tumor recurrence and changes in neurocognitive function.

METHODS

PubMed was queried for studies involving hippocampal-avoidance radiation therapy and results were screened using PRISMA guidelines. Results were analyzed for median overall survival, progression-free survival, hippocampal relapse rates, and neurocognitive function testing.

RESULTS

Of 3709 search results, 19 articles were included and a total of 1611 patients analyzed. Of these studies, 7 were randomized controlled trials, 4 prospective cohort studies, and 8 retrospective cohort studies. All studies evaluated hippocampal-avoidance whole brain radiation treatment (WBRT) and/or prophylactic cranial irradiation (PCI) in patients with brain metastases. Hippocampal relapse rates were low (overall effect size = 0.04; 95% confidence interval [0.03, 0.05]) and there was no significant difference in risk of relapse between the five studies that compared HA-WBRT/HA-PCI and WBRT/PCI groups (risk difference = 0.01; 95% confidence interval [- 0.02, 0.03]; p = 0.63). 11 out of 19 studies included neurocognitive function testing. Significant differences were reported in overall cognitive function and memory and verbal learning 3-24 months post-RT. Differences in executive function were reported by one study, Brown et al., at 4 months. No studies reported differences in verbal fluency, visual learning, concentration, processing speed, and psychomotor speed at any timepoint.

CONCLUSION

Current studies in HA-WBRT/HA-PCI showed low hippocampal relapse or metastasis rates. Significant differences in neurocognitive testing were most prominent in overall cognitive function, memory, and verbal learning. Studies were hampered by loss to follow-up.

Alternate-day fasting for the protection of cognitive impairment in c57BL/6J mice following whole-brain radiotherapy

NLRP3 inflammasome activation is implicated in irradiation-induced cognitive dysfunction. Alternate-day fasting (ADF) has been demonstrated to improve neuroinflammation as a non-pharmacological intervention. However, the exact mechanism and the anti-inflammatory effect in irradiation-induced cognitive dysfunction still need further in-depth study. The present study examined the effects of eight-week ADF on the cognitive functions of mice as well as inflammasome-mediated hippocampal neuronal loss following irradiation in mouse models of irradiation-induced cognitive deficits using seven-week-old male C57BL/6J mice. The behavioral results of novel place recognition and object recognition tasks revealed that ADF ameliorated cognitive functions in irradiation-induced cognitive dysfunction mice. ADF inhibited the expression of components of the NLRP3 inflammasome (NLRP3, ASC, and Cl.caspase-1), the downstream inflammatory factor (IL-1β and IL-18), and apoptosis-related proteins (caspase-3) via western blotting. Furthermore, an increased number of neurons and activated astrocytes were observed in the hippocampus using immunohistochemistry and Sholl analysis, which was jointly confirmed by western blotting. According to our study, this is the first time we found that ADF improved cognitive dysfunction induced by irradiation, and the anti-inflammatory effect of ADF could be due to inhibition in NLRP3-mediated hippocampal neuronal loss by suppressing astrocyte activation.

The correlations between psychological distress, cognitive impairment and quality of life in patients with brain metastases after whole-brain radiotherapy

BACKGROUND

Psychological distress and cognitive impairment are highly prevalent among patients with brain metastases after whole-brain radiotherapy (WBRT). Our purpose was to evaluate the correlations between psychological distress, cognitive impairment and quality of life in patients with brain metastases after WBRT.

METHODS

Seventy-one patients with brain metastasis treated with WBRT were enrolled in this study and were investigated with several scales, including the Montreal Cognitive Assessment Scale (MoCA), the Functional Assessment of Cancer Therapy-Cognitive Function version 3 (FACT-Cog, version 3), the Functional Assessment of Cancer Therapy-Brain Module version 4 (FACT-Br, version 4) and the Psychological Distress Thermometer (DT), before and after WBRT.

RESULTS

The MoCA, FACT-Cog and FACT-Br scores in patients with brain metastases were significantly decreased after WBRT compared with before WBRT (z = - 7.106, - 6.933 and - 6.250, respectively, P < 0.001), while the DT scores were significantly increased (z = 6.613, P < 0.001). There was an obvious negative correlation between the DT score and the FACT-Cog score (r = - 0.660, P < 0.001), a significant negative correlation between the DT score and the FACT-Br score (r = - 0.833, P < 0.001), and an obvious positive correlation between the FACT-Cog score and the FACT-Br score (r = 0.603, P < 0.001). These results suggest that WBRT can cause cognitive impairment in patients with brain metastases, increase their psychological distress and reduce their quality of life (QOL).

CONCLUSION

After receiving WBRT, the cognitive function and QOL of patients with brain metastases were decreased, while psychological distress increased. The cognitive impairment and the decline of QOL after WBRT are associated with increased psychological distress, and that the decline of QOL is associated with cognitive impairment of patients.

Graded Prognostic Assessment (GPA) for Patients With Lung Cancer and Brain Metastases: Initial Report of the Small Cell Lung Cancer GPA and Update of the Non-Small Cell Lung Cancer GPA Including the Effect of Programmed Death Ligand 1 and Other Prognostic Factors

PURPOSE

Patients with lung cancer and brain metastases represent a markedly heterogeneous population. Accurate prognosis is essential to optimally individualize care. In prior publications, we described the graded prognostic assessment (GPA), but a GPA for patients with small cell lung cancer (SCLC) has never been reported, and in non-small cell lung cancer (NSCLC), the effect of programmed death ligand 1 (PD-L1) was unknown. The 3-fold purpose of this work is to provide the initial report of an SCLC GPA, to evaluate the effect of PD-L1 on survival in patients with NSCLC, and to update the Lung GPA accordingly.

METHODS AND MATERIALS

A multivariable analysis of prognostic factors and treatments associated with survival was performed on 4183 patients with lung cancer (3002 adenocarcinoma, 611 nonadenocarcinoma, 570 SCLC) with newly diagnosed brain metastases between January 1, 2015, and December 31, 2020, using a multi-institutional retrospective database. Significant variables were used to update the Lung GPA.

RESULTS

Overall median survival for lung adenocarcinoma, SCLC, and nonadenocarcinoma was 17, 10, and 8 months, respectively, but varied widely by GPA from 2 to 52 months. In SCLC, the significant prognostic factors were age, performance status, extracranial metastases, and number of brain metastases. In NSCLC, the distribution of molecular markers among patients with lung adenocarcinoma and known primary tumor molecular status revealed alterations/expression in PD-L1 50% to 100%, PD-L1 1% to 49%, epidermal growth factor receptor, and anaplastic lymphoma kinase in 32%, 31%, 30%, and 7%, respectively. Median survival of patients with lung adenocarcinoma and brain metastases with 0, 1% to 49%, and ≥50% PD-L1 expression was 17, 19, and 24 months, respectively (P < .01), confirming PD-L1 is a prognostic factor. Previously identified prognostic factors for NSCLC (epidermal growth factor receptor and anaplastic lymphoma kinase status, performance status, age, number of brain metastases, and extracranial metastases) were reaffirmed. These factors were incorporated into the updated Lung GPA with robust separation between subgroups for all histologies.

CONCLUSIONS

Survival for patients with lung cancer and brain metastases has improved but varies widely. The initial report of a GPA for SCLC is presented. For patients with NSCLC-adenocarcinoma and brain metastases, PD-L1 is a newly identified significant prognostic factor, and the previously identified factors were reaffirmed. The updated indices establish unique criteria for SCLC, NSCLC-nonadenocarcinoma, and NSCLC-adenocarcinoma (incorporating PD-L1). The updated Lung GPA, available for free at brainmetgpa.com, provides an accurate tool to estimate survival, individualize treatment, and stratify clinical trials.

Quality of Life and Cognitive Function Evaluations and Interventions for Patients with Brain Metastases in the Radiation Oncology Clinic

Simple Summary

Brain metastases (BMs) are the most common brain malignancy and are projected to increase in incidence over the coming decades. Historically, brain metastasis studies have focused on improving survival outcomes, but recently, the importance of evaluating health-related quality of life (HRQOL) and cognitive function has gained recognition. Although there is a myriad of validated HRQOL and cognitive assessments available in the radiation oncology clinic, there is an urgent need to identify tools tailored to patients with BMs and to adopt a uniform set of tests that measure HRQOL and cognition. This review presents various assessments for measuring HRQOL and cognitive function, current recommendations to improve standardization, and treatments known to preserve HRQOL and cognitive function.

Abstract

Brain metastases (BMs) account for a disproportionately high percentage of cancer morbidity and mortality. Historically, studies have focused on improving survival outcomes, and recent radiation oncology clinical trials have incorporated HRQOL and cognitive assessments. We are now equipped with a battery of assessments in the radiation oncology clinic, but there is a lack of consensus regarding how to incorporate them in modern clinical practice. Herein, we present validated assessments for BM patients, current recommendations for future clinical studies, and treatment advances that have improved HRQOL and cognitive outcomes for BM patients.

Radiation Therapy for Brain Metastases: An ASTRO Clinical Practice Guideline

PURPOSE

This guideline provides updated evidence-based recommendations addressing recent developments in the management of patients with brain metastases, including advanced radiation therapy techniques such as stereotactic radiosurgery (SRS) and hippocampal avoidance whole brain radiation therapy and the emergence of systemic therapies with central nervous system activity.

METHODS

The American Society for Radiation Oncology convened a task force to address 4 key questions focused on the radiotherapeutic management of intact and resected brain metastases from nonhematologic solid tumors. The guideline is based on a systematic review provided by the Agency for Healthcare Research and Quality. Recommendations were created using a predefined consensus-building methodology and system for grading evidence quality and recommendation strength.

RESULTS

Strong recommendations are made for SRS for patients with limited brain metastases and Eastern Cooperative Oncology Group performance status 0 to 2. Multidisciplinary discussion with neurosurgery is conditionally recommended to consider surgical resection for all tumors causing mass effect and/or that are greater than 4 cm. For patients with symptomatic brain metastases, upfront local therapy is strongly recommended. For patients with asymptomatic brain metastases eligible for central nervous system-active systemic therapy, multidisciplinary and patient-centered decision-making to determine whether local therapy may be safely deferred is conditionally recommended. For patients with resected brain metastases, SRS is strongly recommended to improve local control. For patients with favorable prognosis and brain metastases receiving whole brain radiation therapy, hippocampal avoidance and memantine are strongly recommended. For patients with poor prognosis, early introduction of palliative care for symptom management and caregiver support are strongly recommended.

CONCLUSIONS

The task force has proposed recommendations to inform best clinical practices on the use of radiation therapy for brain metastases with strong emphasis on multidisciplinary care.

The Cognitive Effects of Radiotherapy for Brain Metastases

Brain metastases are the most common intracranial neoplasm and are seen in upwards of 10-30% of patients with cancer. For decades, whole brain radiation therapy (WBRT) was the mainstay of treatment in these patients. While WBRT is associated with excellent rates of intracranial tumor control, studies have demonstrated a lack of survival benefit, and WBRT is associated with higher rates of cognitive deterioration and detrimental effects on quality of life. In recent years, strategies to mitigate this risk, such as the incorporation of memantine and hippocampal avoidance have been employed with improved results. Furthermore, stereotactic radiosurgery (SRS) has emerged as an appealing treatment option over the last decade in the management of brain metastases and is associated with superior cognitive preservation and quality of life when compared to WBRT. This review article evaluates the pathogenesis and impact of cranial irradiation on cognition in patients with brain metastases, as well as current and future risk mitigation techniques.

Perihippocampal failure after hippocampal-avoidance whole-brain radiotherapy in cancer patients with brain metastases: Results of a retrospective analysis

Perihippocampal failure is a rare clinical scenario in brain metastatic cancer patients following hippocampal-avoidance (HA) whole-brain radiotherapy (HA-WBRT). The clinical features have not been fully identified because clinical data on intracranial failure after HA-WBRT are limited. It is thus necessary to accumulate clinical data.We retrospectively analyzed cancer patients with brain metastases who were diagnosed between January 2014 and September 2020 at a regional referral hospital. The medical records of patients who underwent HA-WBRT were reviewed. The clinical features of intracranial recurrence were described. Dosimetry parameters were compared in terms of deviation from the recommended protocol of the Radiation Therapy Oncology Report 0933.Twenty-four eligible patients with brain metastases who underwent HA-WBRT were identified; 13 (54%) were male. Seventeen patients (71%) had lung cancer, 6 (25%) had breast cancer, and 1 (4%) had liver cancer. The median overall survival was 12 months. Three patients developed intracranial failure during clinical follow-up, and 2 relapsed with intracranial failure in the perihippocampal region at 13 and 22 months, respectively. The perihippocampal failure rate was about 8%. One patient with small cell lung cancer received HA-prophylactic cranial irradiation; the minimum and maximum doses to the hippocampi were 6.8 and 10.7 Gy, respectively. Another patient with brain metastases from lung adenocarcinoma received HA-WBRT; the minimum and maximum doses to the hippocampi were 5.4 and 10.6 Gy, respectively.We reported unusual cases of intracranial failure in the perihippocampal region following HA-WBRT. Perihippocampal failure could be attributed to an under-dose of radiation partially or be resulted from aggressiveness of cancer per se. Further research on this topic is encouraged.

Evolving management of HER2+ breast cancer brain metastases and leptomeningeal disease

Patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer are at a particularly high risk of breast cancer brain metastasis (BCBM) and leptomeningeal disease (LMD). Improvements in systemic therapy have translated to improved survival for patients with HER2-positive BCBM and LMD. However, the optimal management of these cases is rapidly evolving and requires a multidisciplinary approach. Herein, a team of radiation oncologists, medical oncologists, neuro-oncologists, and breast surgeon created a review of the evolving management of HER2-positive BCBM and LMD. We assess the epidemiology, diagnosis, and evolving treatment options for patients with HER2-positive BCBM and LMD, as well as the ongoing prospective clinical trials enrolling these patients. The management of HER2-positive BCBM and LMD represents an increasingly common challenge that involves the coordination of local and systemic therapy. Advances in systemic therapy have resulted in an improved prognosis, and promising targeted therapies currently under prospective investigation have the potential to further benefit these patients.

Dosimetric feasibility of hippocampal avoidance whole brain radiotherapy with an MRI-guided linear accelerator

Purpose/Objective(s)

Whole brain radiotherapy with hippocampal avoidance (HA‐WBRT) is a technique utilized to treat metastatic brain disease while preserving memory and neurocognitive function. We hypothesized that the treatment planning and delivery of HA‐WBRT plans is feasible with an MRI‐guided linear accelerator (linac) and compared plan results with clinical non‐MRI‐guided C‐Arm linac plans.

Materials/Methods

Twelve HA‐WBRT patients treated on a non‐MRI‐guided C‐Arm linac were selected for retrospective analysis. Treatment plans were developed using a 0.35T MRI‐guided linac system for comparison to clinical plans. Treatment planning goals were defined as provided in the Phase II Trial NRG CC001. MRI‐guided radiotherapy (MRgRT) treatment plans were developed by a dosimetrist and compared with clinical plans. quality assurance (QA) plans were generated and delivered on the MRI‐guided linac to a cylindrical diode detector array. Planning target volume (PTV) coverage was normalized to ∼95% to provide a control point for comparison of dose to the organs at risk.

Results

MRgRT plans were deliverable and met all clinical goals. Mean values demonstrated that the clinical plans were less heterogeneous than MRgRT plans with mean PTV V37.5 Gy of 0.00% and 0.03% (p = 0.013), respectively. Average hippocampi maximum doses were 14.19 ± 1.29 Gy and 15.00 ± 1.51 Gy, respectively. The gamma analysis comparing planned and measured doses resulted in a mean of 99.9% ± 0.12% of passing points (3%/2mm criteria). MRgRT plans had an average of 38.33 beams with average total delivery time and beam‐on time of 13.7 (11.2–17.5) min and 4.1 (3.2–5.4) min, respectively. Clinical plan delivery times ranged from 3 to 7 min depending on the number of noncoplanar arcs. Planning time between the clinical and MRgRT plans was comparable.

Conclusion

This study demonstrates that HA‐WBRT can be treated using an MRI‐guided linear accelerator with comparable treatment plan quality and delivery accuracy.

Radiotherapy for HER 2 Positive Brain Metastases: Urgent Need for a Paradigm Shift

Brain metastases (BMs) are common among patients affected by HER2+ metastatic breast cancer (>30%). The management of BMs is usually multimodal, including surgery, radiotherapy, systemic therapy and palliative care. Standard brain radiotherapy (RT) includes the use of stereotactic radiotherapy (SRT) for limited disease and whole brain radiotherapy (WBRT) for extensive disease. The latter is an effective palliative treatment but has a reduced effect on brain local control and BM overall survival, as it is also associated with severe neurocognitive sequelae. Recent advances both in radiation therapy and systemic treatment may change the paradigm in this subset of patients who can experience long survival notwithstanding BMs. In fact, in recent studies, SRT for multiple BM sites (>4) has shown similar efficacy when compared to irradiation of a limited number of lesions (one to three) without increasing toxicity. These findings, in addition to the introduction of new drugs with recognized intracranial activity, may further limit the use of WBRT in favor of SRT, which should be employed for treatment of both multiple-site BMs and for oligo-progressive brain disease. This review summarizes the supporting literature and highlights the need for optimizing combinations of the available treatments in this setting, with a particular focus on radiation therapy.

Managing Central Nervous System Spread of Lung Cancer: The State of the Art

Brain metastases (BrM) are common in both non-small-cell lung cancer and small-cell lung cancer. Substantial progress in BrM management has occurred in the past decade related to advances in both radiation and medical oncology. Recent and ongoing radiation trials have focused on increasing the candidacy for focal therapy of BrM with stereotactic radiosurgery; reducing the toxicity and improving patient selection for whole brain radiotherapy; and, in small-cell lung cancer, evaluating brain magnetic resonance imaging surveillance without prophylactic cranial irradiation, hippocampal avoidance in prophylactic cranial irradiation and whole brain radiotherapy, and the role of upfront stereotactic radiosurgery for BrM. In medical oncology, the development of multiple tyrosine kinase inhibitors with encouraging CNS activity and emerging data on the CNS activity of immune checkpoint inhibitors in some patients have opened the door to novel systemic and multidisciplinary treatment strategies for the management of BrM. Future research will focus on more robust characterizations of the CNS activity of targeted therapy and immunotherapies, as well as optimal integration and patient selection for multidisciplinary strategies involving CNS-active drugs, radiation therapy, and CNS surveillance.

The Risk of Hippocampal Metastasis and the Associated High-Risk Factors in 411 Patients With Brain Metastases

Background and Aims

To retrospectively analyze the incidence of hippocampal metastasis and the associated high-risk factors in patients with brain metastases and evaluate the safety of hippocampal avoidance whole-brain radiation therapy (HA-WBRT).

Methods

We retrospectively analyzed the data of patients with brain metastases diagnosed by contrast-enhanced cranial Magnetic resonance imaging (MRI) at the First Hospital of Lanzhou University from 2017 to 2020. The boundaries of the hippocampus, hippocampus + 5 mm area, hippocampus + 10 mm area, and hippocampus + 20 mm area were delineated, and the distances from the brain metastases to the hippocampus were measured. Univariate and multivariate logistic regressions were adopted to analyze the high-risk factors of hippocampal metastasis.

Results

A total of 3,375 brain metastases in 411 patients were included in the analysis. The metastasis rates in the hippocampus and surrounding areas of the entire group were as follows: 7.3% (30/411) in the hippocampus, 16.5% (68/411) in the hippocampus + 5 mm area, 23.8% (98/411) in the hippocampus + 10 mm area, and 36.5% (150/411) in the hippocampus + 20 mm area. Univariate logistic regression showed that the pathological type, the number of metastases, the maximum diameter of metastases, and the volume of brain metastases were all correlated with hippocampal metastasis. Multivariate logistic regression showed that the pathological type, the number of metastases, and the total volume of metastases were correlated with hippocampal metastasis.

Conclusion

The pathological type, the number of metastases, and the total volume of metastases are the high-risk factors associated with hippocampal metastasis. Small cell lung cancer (SCLC) has a significantly higher rate of hippocampal metastasis than other tumor types. The greater the number and total volume of metastases, the more likely the hippocampal metastasis. For patients with SCLC or a greater number and total volume of brain metastases, the implementation of HA-WBRT may bring a higher risk of tumor recurrence.

Preservation of cognitive function after brain irradiation

OBJECTIVE

Approximately 50-90% of brain metastatic patients who receive radiation therapy (RT) exhibit cognitive decline which may affects the quality of life of cancer survivors. Hence preservation of cognitive functions in brain metastatic patients becomes important. This review aims to evaluates the pathology or mechanism of cognitive function impairment after brain irradiation and strategies available to preserve cognitive function after radiation therapy.

DATA SOURCES

Published articles evaluating the pathology behind radiation induced cognitive impairment and strategies to resolve or preserve cognitive impairment were searched for in scientific databases (eg: PubMed, Scopus, Cochrane database, Google scholar) using keywords including memantine, brain metastases, radiation therapy, pathophysiology, pathogenesis, mechanism and prevention.

DATA SUMMARY

Several hypotheses have been offered to explain the mechanism of radiation induced cognitive decline. Among them, vascular hypotheses play a significant role. Some pharmacological agents have been also tested in patients receiving radiotherapy, memantine was found beneficial based with the reference to existing data.

CONCLUSION

Future studies are required to evaluate the impact of memantine in different types of radiation therapy procedures and its effects on quality of life of brain metastatic survivors.

Oncological Outcomes After Hippocampus-Sparing Whole-Brain Radiotherapy in Cancer Patients With Newly Diagnosed Brain Oligometastases: A Single-Arm Prospective Observational Cohort Study in Taiwan

BACKGROUND

Promisingly, the technique of hippocampus sparing during WBRT (HS-WBRT) might preserve NCFs. In this research, we examined oncological outcomes, with emphasis on neurologic/non-neurologic causes of death, CNS progression, and leptomeningeal disease (LMD) recurrence in cancer patients who underwent HS-WBRT.

METHODS

One hundred and fourteen cancer patients with newly diagnosed brain oligometastases underwent HS-WBRT were consecutively enrolled. The cumulative incidence of cancer-specific deaths (neurologic or non-neurologic), LMD recurrence, and the composite endpoint of CNS progression (CNS-CE) as the first event were computed with a competing-risks approach to characterize the oncological outcomes after HS-WBRT.

RESULTS

Patients with intact brain metastases had a significantly increased likelihood of dying from non-neurologic causes of death associated with early manifestation of progressive systemic disease (hazard ratio for non-neurologic death, 1.78; 95% CI, 1.08-2.95; p = 0.025; competing-risks Fine-Gray regression), which reciprocally rendered them unlikely to encounter LMD recurrence or any pattern of CNS progression (HR for CNS-CE as the first event, 0.13; 95% CI, 0.02-0.97; p = 0.047; competing-risks Fine-Gray regression). By contrast, patients with resection cavities post-craniotomy had reciprocally increased likelihood of CNS progression which might be associated with neurologic death eventually.

CONCLUSIONS

Patterns of oncological endpoints including neurologic/non-neurologic death and cumulative incidence of CNS progression manifesting as LMD recurrence are clearly clarified and contrasted between patients with intact BMs and those with resection cavities, indicating they are clinically distinct subgroups.

TRIAL REGISTRATION

ClinicalTrials.gov, Identifier: NCT02504788, NCT03223675.

Glial activation positron emission tomography imaging in radiation treatment of breast cancer brain metastases

Brain metastases affect more breast cancer patients than ever before due to increased overall patient survival with improved molecularly targeted treatments. Approximately 25–34% of breast cancer patients develop brain metastases in their lifetime. Due to the blood–brain barrier (BBB), the standard treatment for breast cancer brain metastases (BCBM) is surgery, stereotactic radiosurgery (SRS) and/or whole brain radiation therapy (WBRT). At the cost of cognitive side effects, WBRT has proven efficacy in treating brain metastases when used with local therapies such as SRS and surgery. This review investigated the potential use of glial activation positron emission tomography (PET) imaging for radiation treatment of BCBM. In order to put these studies into context, we provided background on current radiation treatment approaches for BCBM, our current understanding of the brain microenvironment, its interaction with the peripheral immune system, and alterations in the brain microenvironment by BCBM and radiation. We summarized preclinical literature on the interactions between glial activation and cognition and clinical studies using translocator protein (TSPO) PET to image glial activation in the context of neurological diseases. TSPO-PET is not employed clinically in assessing and guiding cancer therapies. However, it has gained traction in preclinical studies where glial activation was investigated from primary brain cancer, metastases and radiation treatments. Novel glial activation PET imaging and its applications in preclinical studies using breast cancer models and glial immunohistochemistry are highlighted. Lastly, we discuss the potential clinical application of glial activation imaging to improve the therapeutic ratio of radiation treatments for BCBM.

Advances in radiotherapy for brain metastases

As novel systemic therapies yield improved survival in metastatic cancer patients, the frequency of brain metastases continues to increase. Over the years, management strategies have continued to evolve. Historically, stereotactic radiosurgery has been used as a boost to whole-brain radiotherapy (WBRT) but is increasingly being used as a replacement for WBRT. Given its capacity to treat both macro- and micro-metastases in the brain, WBRT has been an important management strategy for years, and recent research has identified technologic and pharmacologic approaches to delivering WBRT more safely. In this review, we outline the current landscape of radiotherapeutic treatment options and discuss approaches to integrating radiotherapy advances in the contemporary management of brain metastases.

Influence of Modulation Factor on Treatment Plan Quality and Irradiation Time in Hippocampus-Sparing Whole-Brain Radiotherapy Using Tomotherapy

Objectives: Hippocampus-sparing whole-brain radiotherapy (HS-WBRT) using tomotherapy is known to provide a better dose distribution than volumetric-modulated arc therapy but requires an extended irradiation time. The present study aimed to investigate whether irradiation time can be shortened by reducing the modulation factor (MF) without losing the target dose distribution. Methods: Using six tilted computed tomography images in the head area, the planning target volume (PTV) and hippocampal doses, and the irradiation time was investigated with a jaw width of 1 cm, a pitch of 0.200, and the MF changed from 3.0 to 2.6, 2.2, 1.8, and 1.4. Results: No significant changes in the PTV or hippocampus were found with MF in the range from 3.0 to 1.8, but marked deterioration was found with that of 1.4. The irradiation time showed a linear relationship with the MF within the range from 3.0 to 1.8, with 1334, 1158, 986, and 817 s at modulation factors of 3.0, 2.6, 2.2, and 1.8, respectively. However, when the MF was 1.4, the irradiation time was 808 s. Conclusions: When HS-WBRT is performed with a tilted body position and a jaw width of 1 cm, with a MF of 1.8, a favorable balance between dose parameters and irradiation time is achieved, whereas with a MF of 1.4, the quality of the radiotherapy plan deteriorates, and the irradiation time is approximately the same as that with a MF of 1.8.

Prognostic nutritional index and systemic immune-inflammation index are prognostic biomarkers for non-small-cell lung cancer brain metastases

Aim: This research aimed to elucidate the prognosis values of prognostic nutritional index (PNI) and systemic immune-inflammation index (SII) and clinical characteristics in NSCLC patients with brain metastases (BM) underwent radiotherapy. Materials & methods: Cut-off points of hematological indicators were determined by receiver operating characteristic curve. Overall survival was evaluated by Kaplan-Meier method and Cox proportional hazards model. Results: We retrospectively analyzed 214 patients from January 2009 to December 2018. The result demonstrated the independent prognostic values of PNI (hazard ratio: 0.600; p = 0.004) and SII (hazard ratio: 1.486; p = 0.019). The remaining clinicopathologic factors, including brain radiotherapy modality, smoking history, numbers of brain metastases, intracranial symptoms and Radiation Therapy Oncology Group - recursive partitioning analysis, were independently related to survival (p < 0.05). Conclusion: PNI and SII could be critical prognostic indicators for NSCLC patients with BM.

Stereotactic Radiosurgery for Postoperative Metastatic Surgical Cavities: A Critical Review and International Stereotactic Radiosurgery Society (ISRS) Practice Guidelines

PURPOSE

The purpose of this critical review is to summarize the literature specific to single-fraction stereotactic radiosurgery (SRS) and multiple-fraction stereotactic radiation therapy (SRT) for postoperative brain metastases resection cavities and to present practice recommendations on behalf of the ISRS.

METHODS AND MATERIALS

The Medline and Embase databases were used to apply the Preferred Reporting Items for Systematic Reviews and Meta-Analyses approach to search for manuscripts reporting SRS/SRT outcomes for postoperative brain metastases tumor bed resection cavities with a search end date of July 20, 2018. Prospective studies, consensus guidelines, and retrospective series that included exclusively postoperative brain metastases and had at minimum 100 patients were considered eligible.

RESULTS

The Embase search revealed 157 manuscripts, of which 77 were selected for full-text screening. PubMed yielded 55 manuscripts, of which 23 were selected for full text screening. We deemed 8 retrospective series, 1 phase 2 prospective study, 3 randomized controlled trials, and 1 consensus contouring paper appropriate for inclusion. The data suggest that SRS/SRT to surgical cavities with prescription doses of 30 to 50 Gy equivalent effective dose (EQD) 2₁₀, 50 to 70 Gy EQD2₅, and 70 to 90 EQD2₂ are associated with rates of local control ranging from 60.5% to 91% (median, 80.5%). Randomized data suggest improved local control with single-fraction SRS compared with observation and improved cognitive outcomes compared with whole-brain radiation therapy (WBRT). The toxicity of SRS/SRT in the postoperative setting was limited and is reviewed herein.

CONCLUSIONS

Although randomized data raise concern for poorer local control after resection cavity SRS than WBRT, these findings may be driven by factors such as conservative prescription doses used in the SRS arm. Retrospective studies suggest high rates of local control after single-fraction SRS and hypofractionated SRT for postoperative brain metastases. With a superior neurocognitive profile and no survival disadvantage to withholding WBRT, the ISRS recommends SRS as first-line treatment for eligible postoperative patients. Emerging data suggest that fractionated SRT may provide superior local control compared with single-fraction SRS, in particular, for large tumor cavity volumes/diameters and potentially for patients with a preoperative diameter greater than 2.5 cm.

An Updated Review on Memantine Efficacy in Reducing Cognitive Dysfunction of Whole-brain Irradiation for Adult Patients with Brain metastasis

Context: Increased survival of patients with cancer raises the need to pay attention to long-term side effects. Patients with brain metastasis experienced cognition failure after whole-brain radiotherapy. This review aimed at concluding the efficacy of Memantine in preserving cognitive function by reducing the brain toxicity of whole-brain radiotherapy for metastatic brain cancers. Evidence Acquisition: Published studies evaluating memantine protective effects during brain metastasis radiotherapy were searched for in scientific databases (e.g., Embase, PubMed, Cochrane database, Google Scholar, Scopus) using keywords including whole-brain radiotherapy and Memantine. Results: A total of 4 prospective clinical trials were included in the review. Effects of Memantine on cognition tests were evaluated in these trials. A significantly better Hopkins Verbal Learning Test-Revised (HVLT-R) delayed recognition at months 6 was achieved in RTOG 0614 and NRG CC001. Longer time to cognitive decline was found in the memantine arm of the RTOG trial and was statistically significant. Memantine effects were not statistically significant before 2 months. Conclusions: It seems reasonable to consider Memantine during radiation to prevent long-term cognitive failure in patients with brain metastasis due to the current results. Memantine improves cognition function during whole-brain radiotherapy (WBRT) without adding irreparable complications.