Current Advances and Future Perspectives of Cerebrospinal Fluid Biopsy in Midline Brain Malignancies

CSF Biopsy in Glioma: A Brief Review

Glioma is the most common intracranial malignant tumor. Over the past several years, liquid biopsy in diagnosis and treatment of solid tumors have made many progressions, but there is still a gap from a large clinical application of liquid biopsy in glioma due to many limitations. However, in recent years, researchers have made many explorations into liquid biopsy in glioma. In the future, the liquid biopsy of glioma, especially cerebrospinal fluid, will have a broad prospect. In this review, we will discuss the current research progressions of CSF biopsy in glioma in recent years.

Liquid biopsy and glioblastoma

Glioblastoma is the most common and malignant primary brain tumor. Despite a century of research efforts, the survival of patients has not significantly improved. Currently, diagnosis is based on neuroimaging techniques followed by histopathological and molecular analysis of resected or biopsied tissue. A recent paradigm shift in diagnostics ranks the molecular analysis of tissue samples as the new gold standard over classical histopathology, thus correlating better with the biological behavior of glioblastoma and clinical prediction, especially when a tumor lacks the typical hallmarks for glioblastoma. Liquid biopsy aims to detect and quantify tumor-derived content, such as nucleic acids (DNA/RNA), circulating tumor cells (CTCs), or extracellular vesicles (EVs) in biofluids, mainly blood, cerebrospinal fluid (CSF), or urine. Liquid biopsy has the potential to overcome the limitations of both neuroimaging and tissue-based methods to identify early recurrence and to differentiate tumor progression from pseudoprogression, without the risks of repeated surgical biopsies. This review highlights the origins and time-frame of liquid biopsy in glioblastoma and points to recent developments, limitations, and challenges of adding liquid biopsy to support the clinical management of glioblastoma patients.

Liquid biopsy for children with central nervous system tumours: Clinical integration and technical considerations

Circulating cell-free DNA (cfDNA) analysis has the potential to revolutionise the care of patients with cancer and is already moving towards standard of care in some adult malignancies. Evidence for the utility of cfDNA analysis in paediatric cancer patients is also accumulating. In this review we discuss the limitations of blood-based assays in patients with brain tumours and describe the evidence supporting cerebrospinal fluid (CSF) cfDNA analysis. We make recommendations for CSF cfDNA processing to aid the standardisation and technical validation of future assays. We discuss the considerations for interpretation of cfDNA analysis and highlight promising future directions. Overall, cfDNA profiling shows great potential as an adjunct to the analysis of biopsy tissue in paediatric cancer patients, with the potential to provide a genetic molecular profile of the tumour when tissue biopsy is not feasible. However, to fully realise the potential of cfDNA analysis for children with brain tumours larger prospective studies incorporating serial CSF sampling are required.

Factors Influencing Craniospinal Relapse of Intracranial Germinoma After Complete Remission

OBJECTIVE

To evaluate the pathomechanism of the recurrence of intracranial germinoma after complete response and to confirm the association of the initial magnetic resonance imaging and therapeutic factors with recurrence.

METHODS

This study included patients who were followed up for ≥5 years and who were treated in our hospital from 1980 to 2021. Those with germinoma and germinoma with syncytiotrophoblastic giant cells were diagnosed pathologically. Data were categorizedbased on "gender," "single region," "intraventricular dissemination at the initial diagnosis," "hydrocephalus," "types of radiation therapy (RT)," and "chemotherapy." Fisher's exact probability test was used to assess differences between the no recurrence and recurrence groups.

RESULTS

Among 43 patients, 34 had no recurrence, 5 had delayed recurrence (≥60 months), and 4 had early recurrence (<60 months). Follow-up periods were 143.5 (60-380), 198 (88-222), and 132.5 (75-291) months for the no recurrence, delayed recurrence, and early recurrence groups, respectively. Five patients with delayed recurrence showed 3 intracranial lesions and 2 spinal lesions. Four patients with early recurrence showed 3 intracranial lesions and 1 spinal lesion. Differences in delayed recurrences (focal RT vs. RT including whole-ventricle system; P = 0.0491) were significant in Fisher's exact test.

CONCLUSIONS

RT including the whole-ventricle system reduces delayed craniospinal relapses including dissemination, local, and distant recurrences even ≥5 years after complete response in patients with primary central nervous system germinoma.

Liquid Biopsy and Primary Brain Tumors

Two decades of "promising results" in liquid biopsy have led to both continuing disappointment and hope that the new era of minimally invasive, personalized analysis can be applied for better diagnosis, prognosis, monitoring, and therapy of cancer. Here, we briefly highlight the promises, developments, and challenges related to liquid biopsy of brain tumors, including circulating tumor cells, cell-free nucleic acids, extracellular vesicles, and miRNA; we further discuss the urgent need to establish suitable biomarkers and the right standards to improve modern clinical management of brain tumor patients with the use of liquid biopsy.