He tells a hilarious tale of a post-marketing study of a successful weight-loss remedy that had pounds almost pouring off patients.

Further study called in question the drug's mechanism. It seems a side effect was severe gastric distress and raging diarrhea. Further study showed people who had experienced the side effect, even once, simply chose to avoid food at all costs whenever possible.

In a mid-'70s trial of a cholesterol-lowering drug, the NIH sponsors found that participant side effects varied from one study site to another. It turned out it depended on the order the side effects were listed on the consent form. "If constipation was listed first, that's what you got," Ferguson said.

To the finish line

Avastin has become a frontline treatment for colorectal cancer patients, according to its Web site. Even the earliest study data suggested those who received it lived about four months longer than patients on chemotherapy alone. The drug blocks new vessels and thus tumor growth, said Dr. Graydon Harker, president of Utah Cancer Specialists. The trial looked at whether it, combined with chemotherapy, works better than either one alone.

Physicians say they think they can sometimes tell who's getting what, based on the results. That's true of the pills that Vance is testing in a different clinical trial, as well. Vance said he doubts he's getting the placebo. "I have the side effects, including high blood pressure. And the improvement."

Harker said he's seen some very dramatic results during clinical trials. "Probably better than I had hoped for."

Like all clinical study medications, there are potential problems. Avastin was no exception. Since tumors need new blood vessels to grow, shutting down their development would likely hurt the cancer. But the body needs new blood vessels for tissues that are regenerating, including bone marrow and muscle. There's a risk that needed vessel development could be thwarted. And the list of potential, unknown complications during the trial included concerns about stroke, kidney problems and even contradictory complications, bleeding and clotting.

There were questions besides simple effectiveness, too. Is the drug or the combination more toxic? Does it cause more mouth problems, sores, nausea, vomiting, diarrhea?

Downside with an upside

One downside to clinical trials is patients may not get new medication that could help them. Some receive a placebo.

Still, that's a powerful tool. Doctors know all about the "placebo effect," amazing responses by those receiving nothing more potent than sugar, based on the belief they're getting the study drug.