WASHINGTON — Concerned about the dangers of "market-driven" medical research, key senators are advocating greater protection for patients who enroll in clinical trials.

At a hearing yesterday of a Senate health panel, Sens. Edward Kennedy, D-Mass., and Bill Frist, R-Tenn., called for making the rules that govern testing of human subjects more comprehensive and uniform.

Over the past three decades, researchers have made important advances with drugs and other treatments that began as experiments, often by recruiting volunteers for studies. But critics complain that as research has become a moneymaker for the pharmaceutical and biotechnology industries, inadequate attention has been given to protecting patients.

The bipartisan call for reform comes after reports of problems in clinical research at some of the nation's most highly regarded medical centers, including Johns Hopkins University in Baltimore and the Fred Hutchinson Cancer Research Center in Seattle.

But whether the reforms should be mandatory or voluntary remains a sticking point between Kennedy and Frist.

Kennedy, chairman of the Health, Education, Labor and Pensions Committee, believes mandatory reforms are necessary.

"Numerous expert reports and investigations on our current system of protections have identified serious flaws that must be corrected," he said.

But Frist, a physician, favors voluntary standards, saying they would be adopted more quickly. Additionally, he wants the oversight for clinical trials — now involving more than a dozen federal agencies — to be consolidated into an independent, free-standing office.

"There are too many people using too many different standards with duplication (and) inconsistencies," Frist said.

The Senate hearing — "Protecting Human Subjects in Research: Are Current Safeguards Adequate?" — reflects the increased scrutiny being cast on medical institutions for risks they took with volunteers.

Nearly a year ago, the federal Office of Human Research and Protections opened an investigation into the Fred Hutchinson Cancer Research Center following a series of Seattle Times articles about a controversial cancer experiment there.

The Times reported that patients were deprived of information about the risks and alternatives in a blood-cancer experiment in the 1980s and '90s. They also were not told of their doctors' financial interests in the experimental treatment.

In June, the federal Food and Drug Administration suspended three other clinical trials at "The Hutch" for various problems, including providing inadequate information to patients.

An internal advisory committee has recommended sweeping changes at the Seattle research center, reforms that have been under consideration since last fall. Sen. Patty Murray, D-Wash., said those recommendations will be helpful as Congress moves forward.

Murray questioned whether "informed consent" is living up to its name and whether patients understand financial links between researchers and companies that fund their work.

"We are in a market-driven research arena," she said.

Among other highly publicized problems in recent years:

• At Johns Hopkins last year, three healthy volunteers were enrolled in an asthma study that left Ellen Roche, 24, dead from respiratory failure one month after she inhaled a toxic dose of a chemical. The principal researcher missed information about the chemical's possible hazards.

• At the University of Pennsylvania, a gene-therapy study to treat enzyme disorders killed Jesse Gelsinger, 18, in 1999. The lead researcher had a 30 percent stake in the company that owned the licensing rights to the drug being studied.

• At the University of Oklahoma, researchers tested a vaccine for melanoma on 94 patients with advanced stages of the disease. About a third of the patients had serious side effects. The study was continued on a pregnant woman, despite warnings on the consent form about birth defects.

Cherlynn Mathias, the registered nurse who blew the whistle on the doctor running the Oklahoma study, said her performance was often measured in how many people she enrolled in clinical trials — one of many possible conflicts of interest researchers face.

Among suggested reforms, she proposed having a third party present when medical experts give patients the option of experimental treatments. Patients sign up "often because they are desperate," Mathias testified.

David Charles, chairman of the National Alliance of Medical Researchers and Teaching Physicians, argued that patients take part in studies to help people who may get sick in the future.

He said he hopes to see Congress simplify and clarify clinical-research regulations, but advises caution.

Charles worries that a few failures are being measured against a century's worth of success. "Society loses if regulations to protect the public become obstacles to serving the public," he said.

A spokesman for the biotechnology industry said researchers recognize that changes are inevitable.

"Participants in research are volunteers, meaning that we must do all we can to ensure that they have the utmost confidence that they will be protected," said Charles Johnson, representing the Biotechnology Industry Organization. "Medical research has and will continue to lead to cures and treatments for millions of Americans suffering from diseases."

The House is also looking at clinical-trial reform. Next week, Rep. Diana DeGette, D-Colo., plans to re-introduce the Human Research Subject Protections Act, which languished when first offered in 2000.