Blind mole rats cannot get cancer, and scientists have figured out why: The mammals produce a protein to kill their own cells when they multiply too much.
The mole rats, which were studied by British researchers, can get cancerous cells. But when those cells reproduce too much — after 20 multiplications or so, the study found — they begin to create a protein to kill themselves. Thus the cancer is programmed to eliminate itself.
See the story at Wired.