On Sept. 1, 2025, a multi-institutional study suggests that typically classifiication of meningiomas by appearances may be deceiving — the most common type of brain tumor — into three grades, ranging from slow-growing to aggressive. If a tumor shows activity in a gene called telomerase reverse transcriptase (TERT), it tends to recur more quickly, even if it looks low-grade under the microscope.

If a tumor shows activity in a gene called telomerase reverse transcriptase (TERT), it tends to recur more quickly, even if it looks low-grade under the microscope. Meningiomas — tumors of the meninges, the protective tissue that surrounds the brain and spinal cord — are generally considered benign. But a small subset of these tumors has a mutation in the TERT gene, which is linked to faster growth and a shorter time before the tumor returns after treatment.

TERT is the active part of telomerase, an enzyme that maintains telomeres, the protective ends of chromosomes. In most healthy adult cells, TERT is switched off. But if it becomes switched back on, it can fuel cancer development by driving unchecked cell growth.

“High TERT expression is strongly linked to faster disease progression,” says Gelareh Zadeh, M.D., Ph.D., a neurosurgeon at Mayo Clinic and senior author of the study. “This makes it a promising new biomarker for identifying patients who may be at greater risk of developing aggressive disease.”

In this study, the researchers wanted to see whether high TERT expression, even in the absence of the TERT genetic mutation, also predicted worse outcomes. They looked at more than 1,200 meningiomas from patients across Canada, Germany and the U.S., and they found that nearly one-third of them had high TERT expression despite not having the mutation.

The findings suggest that testing for TERT activity could help doctors predict which patients are at higher risk for recurrence and may need closer monitoring or more intensive treatment. The findings were published in Lancet Oncology, could significantly change how doctors diagnose and treat meningiomas.

The team is currently investigating ways to incorporate TERT expression into the clinical workflow. The research is part of a larger effort at Mayo Clinic called the Precure initiative, focused on developing tools that empower clinicians to predict and intercept biological processes before they evolve into disease or progress into complex, hard-to-treat conditions.