A Simple Blood Test Might Be Able to Predict Brain Cancer Survival

A new study from Penn Medicine found that liquid biopsies may be effective in tracking disease progression in patients with glioblastoma.

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Glioblastoma multiforme (GBM) is one of the most common and deadliest forms of brain cancer in adults. An estimated 14,000 new cases of GBM are diagnosed each year in the United States, according to The National Cancer Institute, and patients with GBM rarely survive 15 months beyond their initial diagnosis. Hence, every step toward an improved forecast of the course of the disease is crucial.

Doctors typically use MRI scans or repeat brain surgeries to diagnose and track changes in GBM tumors, but a new study says a simple blood test could replace the need for more invasive methods.

Led by researchers from the Abramson Cancer Center of the University of Pennsylvania, the study found that a liquid biopsy, a blood test that measures the amount of cell-free DNA (cfDNA) in the bloodstream, may provide better insight on how patients will progress after they are diagnosed with GBM.

“Doctors have begun using liquid biopsies more frequently to monitor certain cancers, particularly lung cancer, in recent years as research has shown their effectiveness in other disease sites. But until now, there has been little focus on the clinical utility of liquid biopsy in brain tumors,” said Erica L. Carpenter the study’s senior author, a research assistant professor of medicine at Penn, and director of the Liquid Biopsy Laboratory.

Researchers tracked disease progression in 42 patients with newly diagnosed GBM by conducting blood tests at diagnosis, before surgery, and at regular intervals throughout their standard of care, chemotherapy and radiation. The 28 patients with a lower concentration of cfDNA — the  circulating DNA that cancer and other cells shed into the blood — before surgery had almost double the progression-free survival than the 14 patients with higher concentrations. The researchers are the first to show that patients with a higher concentration of cfDNA have shorter progression-free survival than patients with less cfDNA, and that cfDNA spikes in patients either at the time of or just before their disease progresses.

One of the challenges in treating GBM is that monitoring imaging can be an inaccurate way to detect disease progression. The tumors themselves usually contain different genetic mutations, which means treatments focused on only one target are ineffective or only partially effective.

Another problem is that trying to track these mutations over time can be difficult, since getting a new tissue sample requires repeat brain surgery. While most patients do have their tumors surgically removed after the initial diagnosis, additional procedures to monitor their disease over the course of treatment can be difficult and are invasive for patients. These issues are especially difficult in patients who experience a recurrence because when GBM comes back it often returns with a vastly different genetic makeup.

The researchers plan to repeat the analysis with a larger group of patients, but they believe these initial findings show promise and may help doctors choose better combination therapies for future GBM patients.

“If our findings are validated by further studies, it would mean that these patients may be able to get a simple blood test that would give us a more accurate assessment than imaging of whether their disease has progressed or not, as well as more data on the mutations in their tumors,” said the study’s lead author Stephen J. Bagley, an assistant professor of Hematology-Oncology at Penn’s Perelman School of Medicine.

“If liquid biopsy can give us a more comprehensive view of the molecular profile of the tumor, we can potentially pick more effective combinations for each patient.”