Thwarting Major Killers/Stopping Cancer Before it Starts; The Quest to Beat Aging; Scientific American Presents; by Ken Howard; 5 Page(s)

To a degree, we are all ticking time bombs. As we eat, sleep, think and work, our cells divide again and again. Randomly over time, occasional bad copies are created. Meanwhile external insults such as tobacco smoke trigger other mutations. Most of the sinister cells are too crippled to survive, but some do. And sometimes they undergo further aberrations. When enough mutations have occurred, the result can be cancer.

"We are all walking around with millions of premalignant cells," explains Robert A. Weinberg, professor of biology at the Massachusetts Institute of Technology's Whitehead Institute. "If we live long enough, we'll all come down with one form of cancer or another."