Scientists have discovered two genes that appear responsible for one of the most aggressive forms of brain cancer.
Glioblastoma multiforme rapidly invades the normal brain, producing inoperable tumours, but scientists have not understood why it is so aggressive.
The latest study, by a Columbia University team, published in Nature, pinpoints two genes.
The researchers say that the findings raise hopes of developing a treatment for the cancer.
It means we are no longer wasting time developing drugs against minor actors in brain cancer - we can now attack the major players
Dr Antonio Iavarone
The genes - C/EPB and Stat3 - are active in about 60% of glioblastoma patients.
They appear to work in tandem to turn on many other genes that make brain cells cancerous.
Patients in the study whose tumours showed evidence of both genes being active died within 140 weeks of diagnosis.
In contrast, half of patients without activity from these genes were alive after that time.
Lead researcher Dr Antonio Iavarone described the two genes as the disease's master control knobs.
He said: "When simultaneously activated, they work together to turn on hundreds of other genes that transform brain cells into highly aggressive, migratory cells.
"The finding means that suppressing both genes simultaneously, using a combination of drugs, may be a powerful therapeutic approach for these patients, for whom no satisfactory treatment exists."
When the researchers silenced both genes in human glioblastoma cells, it completely blocked their ability to form tumours when injected in a mouse.
The Columbia team is now attempting to develop drugs they hope will achieve the same effect.
Using state-of-the-art techniques, they effectively mapped out the comprehensive and highly complex network of molecular interactions driving the behaviour of glioblastoma cells.
Dr Iavarone said: "The identification of C/EPB and Stat3 came as a complete surprise to us, since these genes had never been implicated before in brain cancer
"From a therapeutic perspective, it means we are no longer wasting time developing drugs against minor actors in brain cancer - we can now attack the major players."
Nell Barrie, science information officer at Cancer Research UK, said: "This research is exciting, as it sheds light on the key changes that drive cells in the brain to become glioblastoma cells.
"By finding out exactly how healthy cells turn into cancer cells, scientists hope to find clues for preventing or reversing the process."The technique used in this study should help scientists to understand these changes in other types of cancer, leading to new and more personalised treatment approaches in the future.