Despite the improvement in cancer screening and treatment, removing brain tumors has remained a dangerous skill. Being off by a single millimeter can drastically change the patient's quality of life and it is nearly impossible to determine if any damage was caused by the tumor itself or the surgery. What's more, cancerous tissue in the brain looks nearly exactly like healthy tissue.

It was these facts with which Jim Olson, a pediatric neuro-oncologist at the Seattle Children's Hospital, was confronted a few years ago. A 17-year-old girl had just undergone surgery to remove a brain tumor. An MRI scan revealed that there still remained a thumb-sized piece of the tumor in her brain. On the surgical table, it had looked exactly like healthy tissue. The chief of neurosurgery challenged Olson to find a solution.

Along with a neurosurgical resident, he found one. They discovered a scorpion toxin that would do the trick, binding to cancerous tissue but not its healthy counterparts. When they created a synthetic version of the toxin, they found that it could move across the blood-brain barrier, a difficult hurdle for any drug to clear. It can light up in near-infrared light, which the researchers call "tumor paint".

Their research has been tested in mice. They injected the toxin into a vein in the tail of a mouse that had been implanted with a human tumor. Within 15 to 20 minutes, the tumor began to glow, distinct from the rest of the mouse's body.

Researchers also believe that the technology has the capability to light up tumors outside of the brain, like prostate, breast, and colon tumors.

Though the toxin comes from venom, the researchers say that it appears to be safe. Seattle company Blaze Bioscience licensed the technology. Human trials will begin in late 2013.

The story of the discovery is highlighted in the short documentary Bringing Light, which will be screened at the Sundance Film Festival.