WELL, THIS IS THE 21ST CENTURY, YOU KNOW: Brain cancer patients live longer wearing electric cap designed to zap tumors.

The cap, called the Optune, works by sending alternating, intermediate-frequency (200kHz) electrical fields into the brains of cancer patients. The idea is that the electrical fields disrupt cell division, preventing cells from properly lining up their chromosomes during a cellular split. This disruption, the company says, is fatal to cells. But because cancer cells make up the majority of the cells dividing in the brains of adult cancer patients, the treatment is more harmful to tumors than the brain.

Patients are supposed to wear the cap for at least 18 hours every day, as well as stay on a standard chemotherapy, called temozolomide. The Optune has strips of electrodes connected to a small generator that patients can carry around in a bag. The electrical fields cause mild warming, but otherwise they don’t disrupt normal daily life. And patients can wear a hat over their futuristic-looking medical caps.

In the five-year, phase III clinical trial—from July 2009 to November 2014—466 glioblastoma patients were randomly assigned to try out the Optune with their temozolomide treatment, while 229 others took just temozolomide.

The median overall survival jumped from 16 months among patients on the standard chemotherapy to 21 months for those also using the Optune, researchers found. In the first two years, the Optune seemed to boost patient survival rates from 31 percent to 43 percent. At three years, survival went from 16 percent to 26 percent. And at four years, standard treatment patients had an 8 percent survival rate, while cap-wearers had a 20 percent rate. At five years, survival rates jumped from 5 to 13 percent.

Those are impressive numbers for a new treatment for an almost-universally fatal cancer.