Patients with glioblastoma experienced slightly better overall survival and delayed recurrence of their brain cancer if their heads were exposed to a type of electromagnetic field therapy alongside conventional chemotherapy, the Swiss research team found.
This therapy, called tumor-treating fields, already is approved in the United States and could prove useful in tackling other forms of cancer, said lead researcher Dr. Roger Stupp, chairman of the department of oncology and cancer center at the University Hospital Zurich.
“This treatment may soon become a valuable addition to many situations where improved local tumor control by a noninvasive treatment is of importance,” Stupp said.
The tumor-treating field device resembles a swimmer’s cap, with insulated electrodes lining the interior, explained Dr. John Sampson, chief of neurosurgery at the Duke University School of Medicine, in Durham, N.C. Wires run from the cap to a battery-powered backpack.
When placed on a shaved head, the electrodes in the cap deliver low-intensity alternating electric fields to the brain, Sampson said.
These electric waves are believed to interfere with cancer cells’ ability to divide, slowing the progress of a tumor or even causing it to shrink, Stupp said.
The trial was funded by the device’s manufacturer, Novocure.
The study focused on people suffering from glioblastoma, which the researchers referred to as the most devastating malignancy of the central nervous system in adults. The cancer forms from the glue-like supportive tissue of the brain known as glial tissue, according to the U.S. National Cancer Institute.
Most patients with glioblastoma die within one to two years of diagnosis, the researchers said in background information. During the last decade, they said, all attempts to improve the outcome for patients with glioblastoma have failed in large, randomized trials.
The Swiss research team randomly assigned nearly 700 patients with glioblastoma to one of two follow-up treatments after all had completed chemotherapy and radiation therapy. About two-thirds received the tumor-treating electromagnetic waves plus the chemotherapy drug temozolomide, while the remaining third received temozolomide alone.
People receiving the tumor-treating electromagnetic waves had to shave their scalp and wear the electrode-laced cap at least 18 hours a day, according to the study.
“The device has to be carried around at all times, usually in a small backpack,” Stupp said, noting that the new models weigh about 2 pounds.
People who received the electromagnetic field treatment remained cancer-free an average three months longer than those who got only follow-up chemotherapy — 7.1 months compared with four months, the researchers reported.
Average overall survival also was about five months longer, amounting to 20.5 months in the tumor-treating fields group versus 15.6 months in the chemotherapy-only group.
Patients experienced very few side effects from the electromagnetic wave treatment, with the most common being a rash from the electrode cap. Ointments and steroid creams usually cleared up the problem, Stupp said.
Stupp called the results a step forward in the “management of these patients suffering from this most aggressive and debilitating brain tumor.”
The findings were published Dec. 15 in the Journal of the American Medical Association.
Previous trials involving tumor-treating fields have not produced strong results like these, said Sampson, who wrote a journal editorial accompanying the study.
Because of those mixed early results, and because the therapy is somewhat mysterious, hospitals in the United States have been reluctant to embrace the technology, Sampson said.
“The problem you get into is that you have a therapy with positive survival data in a large trial, but the mechanism is largely unknown,” he said. “It’s sort of like magic, right? It seems to work, but people don’t know why.”
Stupp agreed that cancer doctors are still scratching their heads over the new technology.
“The experience and data are consistent and convincing,” Stupp said. “But because it’s a novel and somewhat unusual way to treat cancer it is still met with a lot of skepticism by many of my colleagues and peers.”
One concern is that the new trial wasn’t “blinded.” That meant that patients knew they were being treated with electromagnetic fields, and that could have influenced the results, Sampson said.