Preventive Effect of Hippocampal Sparing on Cognitive Dysfunction of Patients Undergoing Whole-Brain Radiotherapy and Imaging Assessment of Hippocampal Volume Changes

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.

Radiotherapy for non-cancer diseases: benefits and long-term risks

PURPOSE

The discovery of X-rays was followed by a variety of attempts to treat infectious diseases and various other non-cancer diseases with ionizing radiation, in addition to cancer. There has been a recent resurgence of interest in the use of such radiotherapy for non-cancer diseases. Non-cancer diseases for which use of radiotherapy has currently been proposed include refractory ventricular tachycardia, neurodegenerative diseases (e.g. Alzheimer's disease and dementia), and Coronavirus Disease 2019 (COVID-19) pneumonia, all with ongoing clinical studies that deliver radiation doses of 0.5-25 Gy in a single fraction or in multiple daily fractions. In addition to such non-cancer effects, historical indications predominantly used in some countries (e.g. Germany) include osteoarthritis and degenerative diseases of the bones and joints. This narrative review gives an overview of the biological rationale and ongoing preclinical and clinical studies for radiotherapy proposed for various non-cancer diseases, discusses the plausibility of the proposed biological rationale, and considers the long-term radiation risks of cancer and non-cancer diseases.

CONCLUSIONS

A growing body of evidence has suggested that radiation represents a double-edged sword, not only for cancer, but also for non-cancer diseases. At present, clinical evidence has shown some beneficial effects of radiotherapy for ventricular tachycardia, but there is little or no such evidence of radiotherapy for other newly proposed non-cancer diseases (e.g. Alzheimer's disease, COVID-19 pneumonia). Patients with ventricular tachycardia and COVID-19 pneumonia have thus far been treated with radiotherapy when they are an urgent life threat with no efficient alternative treatment, but some survivors may encounter a paradoxical situation where patients were rescued by radiotherapy but then get harmed by radiotherapy. Further studies are needed to justify the clinical use of radiotherapy for non-cancer diseases, and optimize dose to diseased tissue while minimizing dose to healthy tissue.

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.

Actual, Personalized Approaches to Preserve Cognitive Functions in Brain Metastases Breast Cancer Patients

Simple Summary

Breast cancer is the one of most common causes of brain metastases among solid malignancies, being responsible for 10–16% of all brain metastases in oncological patients. Brain metastases in the course of breast cancer significantly worsen quality of life of patients, especially in the aspect of neurocognitive domains. The review aims to summarize and integrate the current knowledge about breast cancer brain metastases, focusing on indications of certain types of treatment, and with special attention to the role of hippocampus sparing in preserving neurocognitive functions in irradiated patients.

Abstract

Breast cancer (BC) is the most often diagnosed cancer among women worldwide and second most common cause of brain metastases (BMs) among solid malignancies being responsible for 10–16% of all BMs in oncological patients. Moreover, BMs are associated with worse prognosis than systemic metastases. The quality of life (QoL) among brain metastases breast cancer (BMBC) patients is significantly influenced by cognitive functions. Cancer-related cognitive deficits and the underlying neural deficits in BMBC patients can be caused via BMs per se, chemotherapy administration, brain irradiation, postmenopausal status, or comorbidities. Brain RT often leads to cognitive function impairment by damage of neural progenitor cells of the hippocampus and hence decreased QoL. Sparing the hippocampal region of the brain during RT provides protective covering of the centrally located hippocampi according to the patient’s clinical requirements. This article discusses the personalized strategies for treatment options to protect cognitive functions in BMBC patients, with special emphasis on the innovative techniques of radiation therapy.