But two years ago, Mr. Smith began taking an experimental pill along with chemotherapy, and his tumors disappeared. He dropped the chemotherapy nearly a year ago but still takes the pill twice a day. And his disease, though it may return one day, is still at bay.

....The pill Mr. Smith takes, known by the awkward code name BAY 43-9006, could reach the market in one to three years. It is one of a new generation of "targeted" therapies that are transforming cancer treatment by attacking the underlying molecular mechanisms of the disease.

Some experts see Mr. Smith's experience as a harbinger of a future in which cancer, while not cured, will be held in check for years by drugs tolerable enough to take on a continuing basis.

"Cancer will become a chronic disease that we will manage much the same way we manage high blood pressure or diabetes," said Dr. Andrew C. von Eschenbach, the director of the National Cancer Institute.

Dr. Harold Varmus, president of the Memorial Sloan-Kettering Cancer Center in New York, warns against setting strict timetables that would create "false expectations." But he agreed that it was now a "reasonable goal to dramatically reduce death from cancer, making it a chronic disease."

....There have already been some heralded successes with these newer cancer drugs. Gleevec, a Novartis drug, has had striking results in chronic myelogenous leukemia and a rare gastric cancer. Avastin, a recently approved drug from Genentech that blocks the flow of blood to tumors, extended lives of colon cancer patients by about five months in a clinical trial.

The enthusiasm has also spread to the pharmaceutical industry, where cancer, once neglected, has become by some measures the most popular disease target. Biotechnology companies in particular view cancer, a disease caused by genes gone awry, as a good match for their techniques of genetic engineering and molecular biology.

Surveys over the last couple of years by the Pharmaceutical Research and Manufacturers of America found 395 drugs in clinical trials for cancer, compared with 122 for heart disease and stroke combined and 176 for neurological disorders. Another survey of only biotechnology-related drugs in clinical trials found nearly half were for cancer, far more than for any other disease.

....Still, there is a long way to go to make cancer a chronic disease. One of the biggest pieces of news at the conference here is that a targeted drug, Tarceva, extended lives of patients with advanced lung cancer. But when the results are announced, the extension is expected to be only a couple of months.