The proposal is hypothesis-generating: the article does not establish an objective EV-based monitoring test, and the approach requires prospective validation before it could guide patient care. CRCI can occur before, during or after anticancer therapy and may affect learning, memory, attention, processing speed and executive function. It can affect employment, medication management, independence and quality of life, but its severity, affected cognitive domains and temporal course vary substantially among individuals.

Cancer itself, systemic responses to the disease, individual susceptibility and treatment may contribute through overlapping mechanisms rather than one sequential neurotoxic pathway. Proposed processes include neuroinflammation, oxidative stress, mitochondrial dysfunction, blood–brain barrier and neurovascular dysfunction, impaired neurogenesis, altered synaptic plasticity, and oligodendrocyte and white-matter injury. These alterations may involve neurons, oligodendrocytes, astrocytes, microglia and cells of the neurovascular unit, potentially disrupting cellular homeostasis, synaptic connectivity, myelination and neural networks.

Current assessment of CRCI relies primarily on patient-reported symptoms and standardized neuropsychological testing, which provide complementary but not necessarily concordant information. Neuropsychological tests can characterize the presence, severity and domains of cognitive dysfunction, while symptom reports capture experiences that performance testing may not reveal. Neither directly measures the molecular and cellular processes occurring within the living human brain.

Repeated assessment can also be constrained by time, specialist expertise, practice effects and limited scalability in routine oncology. The perspective identifies this as an unmet need for a framework capable of examining biological changes longitudinally across the cancer-care continuum, potentially clarifying when brain-related changes emerge, how they relate to cognitive trajectories and whether they persist or resolve after therapy. In the proposed framework, vesicles enriched with neuron-associated markers, termed neuron-derived EVs, are considered candidate sources of information about neuronal and synaptic processes.

Vesicles enriched with oligodendrocyte-associated markers, termed oligodendrocyte-derived EVs, may provide complementary information about oligodendrocyte and myelin biology. The initial framework focuses on these populations because neuronal signaling and myelin-dependent axonal connectivity represent two complementary components of neural-network function. Astrocyte-, microglia- and vascular-cell-associated EVs could provide additional information in future studies, but they are not part of the framework presented here.

These populations are operationally defined by the markers used to enrich them, rather than by definitive proof that every isolated vesicle came from the brain or from one particular cell type. Previous studies discussed in the perspective used myelin oligodendrocyte glycoprotein, or MOG, to enrich oligodendrocyte-derived EVs and L1 cell adhesion molecule, also called L1CAM or CD171, to enrich neuron-derived EVs. No currently used marker has absolute brain specificity, and expression outside the central nervous system, heterogeneous circulating EV populations and differences in enrichment and detection methods complicate interpretation.

Multimarker characterization, analysis of EV-associated molecular profiles, orthogonal analytical approaches and correlation with independent clinical measures may strengthen the biological meaning of the measurements, but that meaning is not currently assured. Evidence supporting the concept remains preliminary. The author reports a marked reduction in circulating oligodendrocyte-derived EV levels in one individual who developed chemotherapy-associated cognitive impairment.

This single-patient observation cannot establish an association between EV abundance and CRCI; it instead provides a hypothesis for evaluation in larger prospective cohorts. Changes in the abundance of enriched populations also cannot be interpreted directly as loss of tissue integrity, because EV levels may also reflect cellular stress, altered vesicle release or clearance, inflammation and other biological processes. The differing proteins included dynamin-1, cofilin-1, ADAM10 and the P2X purinoceptor, associated with synaptic plasticity, as well as tight-junction-associated proteins.

These findings came from plasma EV preparations rather than purified neuron- or oligodendrocyte-derived populations and provide proof-of-concept rather than a validated clinical association. EV cargo may offer several complementary types of information. Membrane proteins can indicate an operational cellular association, while extracellular biomolecules attached to the vesicle surface form a surface interactome, sometimes described as a protein corona.

It remains uncertain whether such surface-associated molecules reflect the vesicle’s original brain microenvironment or are acquired during transit through biological fluids. Proteins, lipids, metabolites and nucleic acids inside a vesicle may reflect aspects of the physiological or pathological state of its cell of origin. Combined analysis of cellular markers, surface-associated molecules and intravesicular cargo could therefore help investigate inflammation, cellular stress, repair, degeneration, synaptic dysfunction and oligodendrocyte or myelin biology.

These remain candidate applications, and the clinical significance of individual molecular profiles has yet to be established. Another central limitation is anatomical precision. A circulating EV enriched with a neuron-associated marker cannot currently reveal whether the relevant neuron originated in the hippocampus, prefrontal cortex or another region implicated in CRCI.

Neuroimaging provides regional information about structural and functional alterations, while cognitive testing characterizes the severity and pattern of cognitive dysfunction. EV measurements could add a molecular and cellular dimension without replacing either approach. Prospective studies should therefore collect vesicle measurements alongside standardized neuropsychological assessments, patient-reported outcomes and neuroimaging, ideally beginning before treatment and continuing during therapy and into survivorship.

Such studies would need to establish whether EV trajectories provide information beyond existing assessment modalities and whether molecular, imaging and cognitive changes occur in related temporal patterns. Methodological standardization is essential because blood collection, processing, storage conditions and freeze–thaw history can influence EV measurements, as can isolation and enrichment methods, candidate markers and analytical platforms. Harmonized protocols, appropriate controls, pretreatment baselines and repeated sampling would be needed to assess reproducibility and separate cognitive-specific signals from the broad physiological effects of cancer and therapy.

Potential confounders include age, cancer type and stage, systemic inflammation, fatigue, anemia, sleep disturbance, psychological factors, hormonal changes, medications and comorbidities. The perspective’s immediate contribution is therefore a testable research agenda rather than a clinical solution. Future studies would need to demonstrate analytical validity, biological relevance and incremental value when EV results are combined with cognitive and neuroimaging assessments.

They would also need to determine whether a more informative signal lies in EV abundance, altered release or clearance, surface-associated molecules or intravesicular cargo, and whether any alteration corresponds to particular cognitive domains or imaging findings. The article does not claim that EV levels identify CRCI on their own, that fewer vesicles necessarily indicate damaged brain tissue, or that current evidence justifies changing treatment. Until prospective studies establish those points, circulating brain-associated EVs remain investigational molecular signals that may help researchers examine the heterogeneous biological processes associated with CRCI and assess brain health across cancer care.

Subject of Research: Extracellular-vesicle measurements as a complementary molecular approach to studying cancer-related cognitive impairment.

Article Title: Toward objective brain monitoring of cancer-related cognitive impairment: an extracellular vesicle–based conceptual framework

Article References: Mitsuhashi, M. (2026). Toward objective brain monitoring of cancer-related cognitive impairment: an extracellular vesicle–based conceptual framework. Frontiers in Oncology, 16, Article 1926793. https://doi.org/10.3389/fonc.2026.1926793

Image Credits: AI Generated

DOI: 10.3389/fonc.2026.1926793

Keywords: cancer-related cognitive impairment, extracellular vesicles, brain monitoring, liquid biopsy, oligodendrocytes, synaptic biology, neuropsychological testing, neuroimaging, cancer survivorship, biomarker validation, Toward, objective