Imagine monitoring your brain tumor’s response to treatment without the need for repeated invasive procedures. What once seemed like science fiction is now becoming clinical reality through liquid biopsies—a groundbreaking technology that’s transforming how we detect, monitor, and treat cancer.

For patients with glioblastoma and other brain tumors, liquid biopsies represent a paradigm shift from traditional tissue sampling to a simple blood draw or spinal tap that can provide crucial insights into tumor behavior, treatment response, and disease progression.

What is Liquid Biopsy?

A liquid biopsy is a non-invasive test that detects cancer-related biomarkers in body fluids, primarily blood, but also spinal fluid. Unlike traditional tissue biopsies that require surgical procedures to obtain tumor samples, liquid biopsies analyze circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), and other cancer-related materials that tumors shed into the bloodstream or spinal fluid.

Think of it as finding clues about what’s happening inside your body without having to physically access the tumor site. Just as a blood test can reveal information about your cholesterol levels or blood sugar, liquid biopsies can provide a molecular snapshot of your cancer’s current state.

How Are Spinal Fluid Samples Collected?

For brain tumors, CSF may provide better sensitivity than blood because tumor DNA fragments are closer to the tumor site. This is often collected either through a lumbar puncture or a port that is inserted into the brain itself, sitting under the scalp)

Lumbar Puncture (Spinal Tap): A thin needle is inserted into your lower back with you lying down in a comfortable position. Freezing is given to numb the area. 

• Benefits: Direct access to tumor-derived DNA.
• Risks: Temporary headache, back pain, dizziness, rare bleeding/infection (Bagley et al., 2022). Risk can be reduced by having you stay flat for about an hour after the lumbar puncture.

While this approach stays away from the brain, some of the markers we look for may be too far away from the brain. So the test may be a bit less sensitive. 

The port (also referred to as Ommaya Reservoir): A U-shaped incision is made on the scalp. A nickel sized hole is made on the skull. The catheter that goes into the ventricles is connected to the port, which itself is the size of your finger tip. The port sits under your scalp. 

• Benefits: Directly inserted into the ventricles, near where the brain tumor is. Because the port is left in place, it allows the doctors to repeatedly sample the spinal fluid, allowing them to monitor the tumor. 
• Risks: At the end of the day, this is a surgery on the brain, though minor. Surgical complications including bleeding, infection, seizure, or device malfunction.

Both approaches are safe when performed under medical supervision, but patients should discuss with their care team which is most appropriate for their situation.

Understanding Circulating Tumor DNA (ctDNA): Your Tumor’s Molecular Fingerprint

The Science Behind ctDNA

Circulating tumor DNA is perhaps the most promising component of liquid biopsies. As tumors grow and turn over, they constantly shed tiny fragments of their DNA into the bloodstream or spinal fluid. These DNA fragments carry the same genetic mutations and characteristics as the original tumor, creating a molecular fingerprint that can be detected and analyzed.

Key characteristics of ctDNA:

• Tumor-specific: Contains the same mutations as the primary tumor
• Dynamic: Levels fluctuate based on tumor burden and activity
• Accessible: Can potentially be detected through a simple blood draw or spinal tap

What ctDNA Tells Us

When laboratories analyze ctDNA, they can identify:

• Genetic Mutations: Specific DNA changes that drive tumor growth, such as EGFR amplification or IDH1 mutations in glioblastoma
• Tumor Burden: The amount of ctDNA often correlates with the size and activity of the tumor
• Treatment Resistance: New mutations that develop in response to therapy
• Disease Progression: Increasing ctDNA levels may indicate tumor growth before it’s visible on imaging
• Clonal Evolution: How the tumor is changing genetically over time

Questions to Discuss with Your Healthcare Team

If you’re interested in liquid biopsy testing, consider asking:

1. Are there clinical trials at our center using liquid biopsy technology?
2. Would liquid biopsy testing provide useful information for my specific tumor type?
3. How would liquid biopsy results influence my treatment decisions?
4. What are the costs and insurance coverage considerations?
5. How often would testing be recommended for my situation?

The Future Is in Your Blood/ Spinal Fluid

Liquid biopsies represent just the beginning of a transformation toward more personalized, precise, and patient-friendly cancer care. As technology continues advancing, we’re moving toward a future where cancer monitoring becomes as routine as checking blood pressure, and treatment adjustments happen in real-time based on molecular changes.

For brain tumor patients, this technology offers hope for more effective treatments with dramatically less invasive monitoring. While the field is still evolving, participating in clinical trials using liquid biopsy approaches can provide access to cutting-edge care while contributing to research that will benefit future patients.

Exploring Your Options with WeTrials

At WeTrials, we understand that navigating clinical trial options can feel overwhelming. Our AI-powered platform is designed to simplify your search for liquid biopsy trials and other cutting-edge treatments. Whether you’re newly diagnosed or exploring options for recurrent disease, WeTrials can help you discover clinical trials that match your specific situation.

Ready to explore liquid biopsy clinical trials? Visit WeTrials.com to discover personalized trial options, or connect with our team to learn more about how these revolutionary technologies might fit into your treatment journey.

This article is for educational purposes and should not replace professional medical advice. Always consult with your healthcare team about the most appropriate monitoring and treatment approaches for your specific situation.

References:

1. Bagley, S. J., Nabavizadeh, S. A., Mays, J. J., Till, J. E., Ware, J. B., Levy, S., … & O’Rourke, D. M. (2022). Clinical utility of cerebrospinal fluid circulating tumor DNA analysis in adult patients with primary brain tumors. JCO Precision Oncology, 6, e2200072. Read More
2. Miller, A. M., Shah, R. H., Pentsova, E. I., Pourmaleki, M., Briggs, S., Distefano, N., … & DeAngelis, L. M. (2019). Tracking tumour evolution in glioma through liquid biopsies of cerebrospinal fluid. Nature, 565(7741), 654–658. Read More
3. De Mattos-Arruda, L., Mayor, R., Ng, C. K. Y., Weigelt, B., Martínez-Ricarte, F., Torrejon, D., … & Seoane, J. (2015). Cerebrospinal fluid-derived circulating tumour DNA better represents the genomic alterations of brain tumors than plasma. Nature Communications, 6, 8839. Read More
4. Wang, Y., Springer, S., Zhang, M., McMahon, K. W., Kinde, I., Dobbyn, L., … & Diaz, L. A. (2015). Detection of tumor-derived DNA in cerebrospinal fluid of patients with primary tumors of the brain and spinal cord. Proceedings of the National Academy of Sciences, 112(31), 9704–9709. Read More
5. Wan, J. C. M., Massie, C., Garcia-Corbacho, J., Mouliere, F., Brenton, J. D., Caldas, C., … & Rosenfeld, N. (2017). Liquid biopsies come of age: Towards implementation of circulating tumour DNA. Nature Reviews Cancer, 17(4), 223–238. Read More
6. American Brain Tumor Association (ABTA). (2024). Emerging Diagnostics: Liquid Biopsy for Brain Tumors. Read More
7. WeTrials. (n.d.). WeTrials Study Finder. Read More