There's a glimmer of hope for patients with one of the most deadly forms of brain cancer.

Glioblastoma has a very poor prognosis, but a wearable device called the Optune cap is designed to prevent cancer cells from dividing and spreading.

It sends electrical currents directly to the tumors.

Patients who used it along with chemotherapy survived an average of 21 months. Those who had chemo alone survived an average of 16 months.

The FDA approved the cap in October 2015 for newly diagnosed glioblastoma patients.