The new breast cancer treatment is painful, exhausting and sometimes fatal. At best, it will extend the lives of one in every five patients. And it will be years before anyone knows for sure whether it's an improvement.

But many insurance companies already have decided to pay for it - at $100,000 per patient.Under pressure from enthusiastic physicians and often desperate patients, insurers are paying for medical procedures and tests long before anyone knows when to use them or how well they work.

As a result, medicine is full of procedures and high-tech gizmos that add billions to America's $700 billion health care bill without adding anything to a patient's prognosis.

"It is not inconceivable that reducing unnecessary care could trim $50 billion a year from the nation's medical bill," says Dr. Robert Brook, a research physician at the Rand Corp., a Santa Monica, Calif., think-tank.

"When we pay for very expensive technologies that benefit relatively small numbers of people," says John Cova, director of medical technology assessment for the Health Insurance Association of America, "those costs are passed on to everyone who has health insurance."

Unlike drugs, which face years of tough tests before the federal government approves their use, medical tools and techniques get into doctors' hands "faster than we can assess them," Mr. Cova says.

Sometimes the system works. In the past two years, surgeons around the United States have adopted a new laser-assisted method for removing gall bladders that was invented in Europe, introduced here by a Nashville surgeon and promoted by laser manufacturers. The procedure turned out - in evaluations published months after the operation was widespread - to be an improvement on the old open-belly surgery.

Other times, what's billed as an innovation, really isn't. For instance:

* Machines useful for one condition are sometimes applied to others without much justification. CAT scans are no better than standard chest X-rays for detecting certain tumors, but most radiologists still use the new, expensive instrument instead because they've gotten used to doing so. Cost: $360 instead of $36.

* Multimillion-dollar magnetic resonance imaging (MRI) machines, while valuable for some purposes, are not especially useful for common examinations of the spleen, pancreas and cancer of the liver. Still, they're widely used for those procedures. Cost: $560.

"What (doctors) were seeing were wonderful images, absolutely elegant in their depiction of anatomy," said Herbert Abrams of Stanford University, who headed a federal panel that concluded the MRI images were useless for some


Insurers say there's been a medical "arms race" as competing hospitals are forced to buy the latest gizmos in order to attract doctors - and doctors use them to attract patients.

Some have tried to avoid paying for costly or unproved procedures by stamping them "investigational." But when push comes to shove - or patients come to court - insurance companies often decide it's less expensive to pay for an experimental procedure than to fight every dying patient who sues them, Mr. Cova says.