(MONEY Magazine) – For Fred Holper of Keyport, N.J., facing a diagnosis of terminal colon cancer at the age of 48 was tough, but his treatment decision wasn't. Immediately after surgery in 2001, he joined a clinical trial to try to save his life. The surprise (two surprises, actually) came a year later. First, against most odds, he was still alive--and relatively healthy--despite the cancer that had spread to his liver. Second, he'd received approximately $110,000 worth of then experimental chemotherapy (Avastin) and CAT scans, free of charge. Says Holper: "I am here today for two reasons, my faith and the Avastin."

Holper's may be an unusually strong endorsement of clinical trials. Yet more and more patients are following the same path to gain access to the latest, possibly greatest, but not yet on the market treatments for serious illnesses. For patients, it may mean free drugs, treatment by the field's foremost experts (also gratis) and free follow-up care. But there are serious risks too. Before you venture into the medical frontier, schedule an appointment with the study's medical team and ask these questions.

1) What is the purpose?

The answer isn't always as obvious as it may seem. Many drug or procedural trials are designed not to find a "cure" but to achieve more modest goals--say, to slow down the progress of a disease or to determine whether a drug that has been effective in treating a different condition might work for the illness in question. If you or someone you love is seriously ill, you don't want to sign up for a clinical trial with false expectations of the good that can come of it. So talk to the researchers about the best outcome you can expect and, perhaps more important, the results they consider to be most likely.

2) What are the risks?

Of course, you also need to know the worst-case scenario. In addition to possibly causing side effects, the drugs or procedure under study simply may not work, delaying other needed treatments. Or you could get a placebo, meaning you'd be receiving no help at all. Ask the doctors what could go wrong and how often those problems occur. Then talk to your own doctors to get their take, as well as to patients who have participated in similar trials (ask the researchers for referrals).

3) What's required of me?

Trials vary greatly in how much time and effort is needed. Some, for example, ask you to be available for a full day of blood-work and other testing once or twice a month, or even weekly. That can play havoc with work schedules, says Sharon Lane, a nurse at the Dana-Farber Cancer Institute in Boston. Ask the trial's nurses what's involved. They typically sweat the behind-the-scenes details and may be more current on logistics than the doctors.

4) Who pays?

Sponsors of clinical trials generally pay most of the costs, but not in every case. So be sure to ask. Bear in mind that your regular health plan is still responsible for covering any medical care that's not directly related to the study.

Warning: Insurers may refuse to pay some claims for a patient enrolled in a clinical trial, reports Joni Newman, a nurse with the Rocky Mountain Cancer Centers in Denver. "They say, 'We don't cover experimental drugs' or 'We're not certain whether the health problem was caused by the trial or would have occurred independently,'" she says.

To avoid problems, ask the trial coordinator whether other participants have had run-ins with their insurers and, if so, whether the study team will run interference for you. And check directly with your health plan as well. After all, when you're putting your health on the line--for your own good, but also for the good of medical science--you shouldn't have to go out of pocket for the privilege.

Curtis Pesmen is the author of The Colon Cancer Survivors' Guide.

HOW TO FIND A TRIAL

To learn about clinical trials near you, try these sites

FOR FEDERAL AND PRIVATE STUDIES

See the National Library of Medicine at the National Institutes of Heath (clinicaltrials.gov).

FOR ALTERNATIVE MEDICINE

Try the National Center for Complementary and Alternative Medicine (nccam.nih.gov).

FOR DRUG COMPANY TRIALS

Go to the International Federation of Pharmaceutical Manufacturers & Associations (ifpma.org).