Maybe it's because, from the beginning, the scientists behind this test were only interested in helping mice avoid cancer, or maybe it's because the people in charge are pussies and apparently think a good solid dose of cancer is character-building.
Radioactive Scorpion Venom
If you didn't expect the cure to one of mankind's greatest ills to come from the Israeli Desert Scorpion (also known as the "Deathstalker") raise your hand. If you did, shut up you lying prick. A group of scientists who, evidently, graduated from the Marvel School of Medicine have decided that radioactive scorpion venom will probably cure cancer. The possibility of death and the even greater possibility of the creation of an unstoppable super army of scorpion men is, apparently, a chance we'll just have to take.
The scientists in question took the neurotoxic chemical cocktail from That Which Stalks Death and irradiated it themselves, undoubtedly as preparation for the most epic "I dare you to drink this" in history. Working at the awesomely named "Transmolecular Corporation" in Massachusetts, they found one of the few ingredients in the venom which doesn't kill you.
Instead it binds to cancer cells, presumably on the grounds that if it's come all this way it's going to kill something. If scientists just happen to have made those molecules radioactive, any malignant cells in your body will suddenly find themselves being irradiated to death.
Or, if Marvel is any indication, it'll be, you know, that unstoppable super army thing.