In the case of the flu, the body activates its defenses by producing proteins called cytokines or lymphokines. (It's these proteins, by the way, that make you feel crummy and cause your fever.) The proteins deliver a message to the bone-marrow cells to proliferate; this in turn raises your white-blood-cell count, and the white blood cells then go attack the interloper and kill it.

When the infection is taken care of, the cytokines, the bone marrow, and the white blood cells all return to their normal levels. "The system's got its own internal feedback, and it's all beautifully orchestrated while you're doing everything you normally do," Slamon says.

But what really energizes him is the extraordinary implications. "The most profound orchestration, of course, is the way the entire genetic blueprint is laid out and followed from fertilization to delivery of an infant. Understanding how that happens is, literally, having the keys to life. And we're there now. We're breaking the entire code of the human genome so each gene will be identified and we'll know what each one looks like. To use an analogy, you can't read a book if you don't first know the alphabet. Identifying the genes gives us an alphabet."

The next challenge, in the language of Slamon's analogy, is to use the alphabet to then read and understand the story. "If we know the genes and we understand their functions, we can then actually alter what happens in the body in profound ways," Slamon says on the walk back across campus to his lab in UCLA's Jonsson Cancer Center. "That's both exciting and scary. If we put enough of this information together, it really could be the end of disease as we know it."

Like most successful scientific innovators, Slamon is a zealot. He is convinced he can see things others can't (or won't); he has complete confidence in his vision; and, most important, he is a true believer in the power of science. And at least on part of this particular prophesy, he is not alone.

"We are going to see a global conquering of cancer in the next five to ten years," says Dr. Carlos Cordon-Cardo, the director of molecular pathology at Memorial Sloan-Kettering.

The developments are "the equivalent of going from smoke signals to faxes and e-mails."

The potent combination of knowledge (understanding which questions to ask) and technology (the means to actually get the answers) has begun to move science forward and make things happen at an unprecedented pace. When Slamon first began to look at genes involved in regulating cell growth back in the eighties, it was a cumbersome, exhausting process. He'd have to take a piece of tumor tissue that had been frozen in liquid nitrogen, grind it all up, liquefy it, extract the DNA, and examine one gene at a time for irregularities. This took days to accomplish, and in any event, there were only a handful of genes that had even been identified as being involved in growth.

Now not only are almost all of the body's 70,000 to 100,000 genes identified -- with hundreds so far believed to be involved in growth regulation -- but a researcher can look at thousands of genes at one time thanks to something called micro-array technology. And the data can be analyzed relatively quickly on a desktop computer. It is only a matter of time before every doctor will have the equipment in his office to produce a genetic profile of each patient that could be used for prevention, diagnosis, and treatment.

"This really is a new era," says Sloan-Kettering's Cordon-Cardo. "This is the beginning of medicine that is much more scientific. It is going to change how we practice our specialities, how we diagnose, and how we orient our prognosis."

Both Slamon and Cordon-Cardo say doctors will move away from hit-and-miss empiricism to tools that are much more precise. "Rather than simply looking at tissue and saying, 'This is malignant, and I think it's bad because the cells are not well differentiated and I've seen this many times before,' we will have the technology to determine exactly what's wrong," says Cordon-Cardo.

"We will know why two people with what look like identical tumors under the microscope are responding so differently to treatment -- why one is thriving and the other is dying. And we will be able to use this information to specifically tailor treatment for individual patients. I would say it is the equivalent of society going from smoke signals and banging on drums to faxing and e-mail. This is the kind of technological leap we're looking at."

Slamon says oncology has been at the forefront of the research because it's such a profound disease process and the therapies currently used are so poor. "But this information we're learning from the cancer battles will be really broad-based and far-ranging," he says. "If we can control the genes, meaning that we can turn them on and off, think about the implications for virtually every disease, whether it's diabetes, heart disease, or even aging."

In the case of heart disease, people have heart attacks when blood flow to the heart is impeded and, as a result of this, part or all of the heart muscle dies. But, Slamon says, if scientists know which genes control tissue growth, they could theoretically engineer regeneration to replace the dead heart tissue. Similarly with diabetes, it would be possible to intercede to repair whatever's wrong with the insulin receptors or in the signal-transduction pathways.

"The heart is an extremely complex organism that involves millions of cells connected in an intricate pattern that all have to contract together at the same time to push blood in the right direction," says Dr. Andrew Marks, director of molecular cardiology at Columbia University. "So heart-tissue regeneration is, at best, a long way off."

However, Marks points out that scientists do already understand some of the molecular mechanisms that control cell growth that results in blocked arteries. As a result, drugs to block these pathways have been developed and are already in clinical trials. In addition, markers are also being identified to help in both diagnosis and determining the course of a patient's treatment. Studies have been published, for example, showing that people with an alteration of a receptor in the heart called beta-2 adrenergic suffer the most aggressive heart disease; so their treatment can be planned accordingly.