The pain was incredible. Nothing seemed to ease it. Robert Boyd would try anything for relief — even becoming a “guinea pig” in a clinical trial.

That’s what he did.

About a year later, the 73-year-old Riverside, Calif., man who suffers from osteoarthritis, lives pain-free and is in his second clinical trial. He said he didn’t worry about possible negatives of offering his body to science.

“What did I have to lose?” Boyd said. “I had the pain. I either kept the pain or got rid of the pain. I didn’t think they’d give me anything that would kill me.”

Maybe not, but researchers might have dispensed something that could have hurt, doctors warn. Not intentionally, of course, but clinical trials are experiments and can be risky — even deadly.

Last year, a study for hormone replacement therapy was stopped abruptly after the regimen increased a woman’s risk of heart disease, breast cancer, strokes and blood clots.

“Anything that is truly experimental will always have some unknowns,” said Dr. Mark Pegram, a researcher and oncologist at UCLA’s Jonsson Comprehensive Cancer Center. “There is always a risk of side effects with new treatments. But at some point in history, someone has to go first.”

Virginia Garner, a 58-year-old schoolteacher from Claremont, Calif., was one of those someones — and it saved her life, she claims. Diagnosed with chronic myelogenous leukemia, Garner felt like she was losing the fight of her life.

Her standard treatment, interferon, wasn’t helping. Her weight plummeted from 130 to 103 pounds. She was tired and often feverish. Then she learned about a study at UCLA’s cancer center. Garner applied.

“It was my only hope,” she said. “Looking back, it was kind of a scary thing to do. But when you’re on the edge of death, you’ll take all the risks you need to take.”

Researchers gave her a drug now known as Gleevec. Within two weeks, Garner’s health improved dramatically. The Food and Drug Administration approved the medication in 2001, after just three months of review. Today, it’s the treatment of choice for people with chronic myelogenous leukemia.

“I did it and it’s been the most amazing thing in my life,” Garner said about the clinical trial. “That I have a life is amazing.”

Trials rarely, however, conclude with that level of success. Most are deemed failures, says Dr. Donald Fong, associate director of clinical trials for Kaiser Permanente Southern California.

“It’s better to be given a placebo than the (test) product,” he said. “Most clinical trials are negative. Most products don’t turn out. That’s not to say you shouldn’t participate.”

People interested in a clinical trial must ask many questions about the institutions and treatments involved, Saukel said. And not all trials are regulated by the federal government.

“Are there shady companies? Yeah,” Saukel said.

And no research, even that conducted by the federal government, is immune from criticism.

People most motivated to participate in trials are those like as Boyd and Garner — patients not getting relief from other forms of treatment.

In research there are no guarantees, but each new trial is cause for hope, Pegram said.

“Fortunately, more and more, a lot of things do work out,” he added.