Ask the Doctors - What are clinical trials and how do they work?


Dear Doctors: I keep reading about new cancer drugs that have been developed in clinical trials. What exactly is a clinical trial and how does it work?

A clinical trial is a scientific study that looks into whether a specific drug, medical treatment, device or approach is not only effective, but also safe. Although clinical trials for new drugs often get the most press, other important advances arise from the process. New ways to screen for disease, new methods of diagnosis, and techniques that will improve the quality of life for people living with disease are all important advances made in clinical trials.

New therapies are tested in treatment trials. Prevention trials investigate methods of lowering disease risk. In screening trials, optimal methods to discover the onset of disease are tested. Supportive care trials focus on quality of life for patients with debilitating disease. Diagnostic trials focus on tests and procedures to pinpoint the exact type of cancer or condition a patient has.

So how does a clinical trial work? It starts with an idea. A researcher or doctor or other expert comes up with a "what if?" scenario. For example, what if it's possible to develop a drug to help a patient's own immune system fight cancer?

The next step is extensive laboratory testing. If the idea continues to show promise, research moves into a clinical trial.

A detailed plan, known as a protocol, is created. It states who is eligible to take part in the clinical trial, details all of the tests and procedures that will be performed, names the drugs that will be involved, and describes how the drugs will be administered. The protocol also indicates the length of the clinical trial, and how the information will be collected and collated.

Clinical trials are conducted in four distinct phases that may take place over the course of several years. They begin with Phase 1, which is initial testing on a small group of participants to assess safety and identify side effects. In Phases 2 and 3, the new drug or treatment is given to ever-larger groups of people to further evaluate safety and efficacy. By Phase 4, the drug or treatment has been approved by the FDA and is now evaluated in a large population.

If you're thinking about joining a clinical trial, you should know: -- The specific purpose of the study; -- Why researchers believe the experimental therapy will be effective; -- What drugs, tests or procedures the trial entails; -- Any risks or potential side effects of the treatment; -- How much time is required; -- How your daily life will be affected; -- How you will know whether the therapy is successful.

It's not an exaggeration to say that clinical trials are at the heart of modern medical advances. Many of the cancer treatments that are saving or extending lives today began as a "what if?" idea in a clinical trial. And while participants may join in hopes of being on the receiving end of a medical advance, they also have the satisfaction of knowing that they are contributing to the body of knowledge that will make medicine even more effective in the future.

Learn more about clinical trials at

Eve Glazier, MD., MBA, and Elizabeth Ko, MD., are internists and assistant professors of medicine at UCLA Health.

Ask the Doctors is a syndicated column first published by UExpress syndicate.