Genetic markers provide better Brain Cancer classification

A team of scientists from UC San Francisco and Mayo Clinic has shown that using just three molecular markers will help clinicians classify Gliomas, the most common type of malignant brain tumors, more accurately than current methods.“Unfortunately, classifying a tumor only by appearance and grade has not provided sufficient information about the way the tumor is likely to behave, how it will respond to treatment or the patient’s likely survival time,” said Margaret R. Wrensch, Ph.D. The three markers are a mutation in the region that promotes expression of the gene TERT, which expresses telomerase, an enzyme that helps keep cancer cells alive by protecting structures called telomeres; a mutation in the genes IDH1 or IDH2, referred to collectively as IDH mutation; and a combined mutation that deletes parts of chromosome 1 and chromosome 19.
The scientists found that among grade II and III tumors, 29 percent were “triple positive,” showing all three markers. Patients with these tumors had a median survival time of 13.1 years. Five percent had both TERT and IDH mutations, and had a median survival time similar to triple positive tumors. Forty-five percent had IDH mutation only, and a median survival time of 8.9 years. Seven percent of tumors were triple negative, with none of the mutations, and had a median survival time of 6.2 years. The 10 percent of tumors that only had the TERT mutation were associated with the shortest median survival time – 1.9 years. Wrensch suggested that once these or similar molecular markers are accepted by clinicians as part of the classification system, “it may make a great deal of difference in treatment approach for individual patients.”