Tumor-treating fields (TTFields) are a relatively new form of cancer treatment that send mild electrical fields through the scalp in an effort to block cell division. While it was approved a few years ago, further studies have been ongoing to determine how effective it really is. New results from a clinical trial have found that it significantly improves survival rates in brain cancer patients, with scientists labelling it a once-in-a-decade advance in the area.

The device used in the clinical trial is a patient-operated system called Optune, made by oncology company NovoCure. Through four adhesive patches, or transducer arrays, applied to the scalp, the system continuously delivers low-electric fields at a frequency of 200 kHz, which pulse through the skin and are thought to interrupt the ability of cancer cells to divide.

NovoCure's device was first approved by the US Food and Drug Administration in 2011 for use on glioblastoma, the most aggressive form of brain cancer with a two-year survival rate of around 30 percent. Various trials have investigated its efficacy since then, but the company describes the latest results as "landmark."

Between 2009 and 2014, researchers led by neurologist Roger Stupp from Northwestern University enrolled 695 patients with newly diagnosed glioblastoma in a phase three clinical trial. Two hundred and twenty-nine of those patients were administered an oral chemotherapy drug called temozolomide, while 466 received both temozolomide and treatment with the Optune device.

The median survival rates for patients receiving both was 21 months, compared to 16 months for those receiving temozolomide alone. Two-year survival rates were 43 percent for those receiving both compared to 31 percent, three-year survival rates 26 and 16 percent, four-year survival rates 30 and eight percent and five-year survival rates 13 and five percent. The researchers say that the hazard ratio for overall survival was 0.63, which means that patients receiving the Optune treatment had a 37 percent lower risk of death.

"The last time any form of treatment was shown to improve survival for patients with this disease was more than 10 years ago, when adding temozolomide to radiotherapy was shown to improve the two-year survival rate from 10 percent to 27 percent," said Stupp, "It is very exciting to see that the magnitude of benefit from adding TTFields to temozolomide is similar to that seen from adding temozolomide to radiotherapy; the two-year survival rate for those in the TTFields plus temozolomide arm was 43 percent. These data show the power of this new treatment modality, and we look forward to learning the results of trials testing it in patients with other forms of cancer."

The results of the trial can be accessed online and are being presented at the annual American Association for Cancer Research meeting in Washington this week.

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