You know how people toss around the phrase “the cure is worse than the disease”? They should meet Jim Olson.

Olson, a pediatric oncologist and research scientist in Seattle, has developed a compound he calls Tumor Paint. When injected into a cancer patient, it seems to light up all the malignant cells so surgeons can easily locate and excise them.

But it has an unusual main ingredient: a molecule found in the stinger of Leiurus quinquestriatus, or deathstalker scorpion.

The molecule, chlorotoxin, was already being studied for its potential to kill certain cancer cells; Olson’s big idea was realizing that it attached to any kind of cancer. So when it was linked to a fluorescent material, it lit up cancer cells that no other technology could identify.

The idea of injecting scorpion venom into sick people sounds so bizarre that Olson was unable to raise money from major grant-making organizations, Brendan I. Koerner writes in the July issue of Wired magazine, even though precisely locating cancerous cells is one of the more vexing problems in oncology. But he started raising money from the families of current and former patients and now has enough so his project is in clinical trials.

Olson came to pediatric oncology after realizing he had a “high tolerance for [the] heartbreak” inevitable when treating seriously ill children. Koerner follows him on his rounds: “A fourth-grader who may not live to celebrate another birthday, a teenage girl whose gloomy prognosis has made her suicidal — none of these encounters erase Olson’s tranquil smile.” This “steady bedside manner” has endeared him to many heartsick families. Some critics fear that Koerner may be giving “undue hope” to people with cancer, and others are squeamish about patient-based funding. But Koerner concludes: “Perhaps the ethical purists might feel rather differently if they, like [Olson], had to walk around a pediatric cancer ward every day.”