A type of electromagnetic field therapy called tumor-treating fields may help extend the lives of patients with a brain tumor who also undergo routine chemotherapy, early research suggests. Researchers tested the therapy in people with glioblastoma -- one of the most devastating forms of brain cancer in adults. Most patients die within a year or two of diagnosis, and attempts to improve survival rates over the past decade have failed, the study, published in JAMA, points out. Tumor-treating fields, also referred to as TTFields, work by selectively disrupting the division of cells by delivering low-intensity, intermediate-frequency alternating electric fields to the head.