Cerebrospinal fluid first proven effective in diagnosing cancer

The Gene Expression and Cancer Research Group at the Vall d’Hebron Institute of Oncology (VHIO) has proven for the first time the advantages of analyzing cerebrospinal fluid (CSF) for prognosis, treatment and monitoring of brain tumors. The study led by Dr. Seoane, director of Translational Research at the VHIO and ICREA professor, shows that tumor DNA circulating in the central nervous system is much higher in the CSF than in plasma.

“Our main limitation was that circulating tumor DNA levels for brain tumors are very low in plasma. But the brain has its own closed circuit of fluid, cerebrospinal fluid, which bathes the brain and spinal cord, and is therefore in direct contact with tumor cells and we found circulating tumor DNA in CSF at such high levels that we were able to detect and characterize tumors with a high degree of sensitivity,” explains Dr. Seoane.

The new technique the study proposes is a much less aggressive liquid biopsy than those currently used to extract a sample of brain tissue, as CSF can be obtained through a spinal tap like that used for epidural administration. Samples were traditionally obtained using a needle biopsy or surgery that puts the patient at risk and doesn’t necessarily extract a representative sample of the tumor. Liquid plasma biopsies are highly useful for metastatic colon cancer, breast cancer and lung cancer, but aren’t as successful with brain tumors.

As this is a less-invasive technique, it can be repeated in the same patient to monitor the tumor and its characterization, a process that is essential to treating any tumor in an effective, targeted manner. Furthermore, this monitoring is essential for glioblastoma, the most common, aggressive malignant brain tumor, which nearly always returns after being treated with different genetic alterations than the primary tumor. The new technique allows doctors to more effectively study the situation than traditional techniques. “This new approach to liquid biopsy in CSF could help, in some cases, to consider novel, more specific and targeted experimented therapies, which could in turn also improve clinical response,” explains Dr. Josep Tabernero, director of VHIO and head of the Medical Oncology Department at the Vall d’Hebron University Hospital.

The study would also facilitate and complement diagnosis of leptomeningeal carcinomatosis, the tumor infiltration of the thin film that covers the brain and spinal cord and occurs as a metastasis of other tumors, as it is very difficult to detect tumor cells in this thin layer using a spinal tap.

This groundbreaking research, published in the journal Nature Communications, was made possible thanks to a grant Dr. Seoane received from the Spanish Association Against Cancer (AECC) that allowed them to conduct the studies to test the feasibility of this idea, which will surely change the future of cancer diagnostics.