The NovoTTF-100A system is suitable for adult patients (age 22 or older). Doctors can use it to treat patients with brain cancer (called glioblastoma, or "GBM") which will reappear in higher parts of the brain after receiving chemotherapy (cancer drugs). the NovoTTF-100A system is the replacement of standard medical treatment of GBM and is used alone after using other treatment methods (such as surgery and radiation therapy). The NovoTTF-100A system is a portable device. It generates electric fields which are called tumor treatment fields ("TTFields"). A transducer array connected to the device passes the TTField to your head. TTFields is designed to destroy brain cancer cells.