Should You Take Part in a Clinical Research Trial?
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Should You Take Part in a Clinical Research Trial?

research lab study After thoroughly investigating drugs or other treatments using laboratory animals, researchers design studies, called "clinical trials." The purpose of these trials is to test the treatments' safety and effectiveness in people. To receive approval from the US Food and Drug Administration (FDA) for a new drug, manufacturers must prove that the agent works in humans and is not dangerous. They do this by submitting results from a series of clinical trials.

Many Phases of Study

Clinical trials involve a multiphase process, which usually follows this pattern:

Phase I:

The first phase, typically lasting around 18 months. It tests the safety of using the drug in humans and only enrolls a small number of volunteers. Healthy people usually participate and can tell researchers if they experience side effects. Blood levels of the drug are often measured so that scientists can estimate a likely effective dosage.

Phase II:

About 80% of new drugs are deemed safe and move on to Phase II. This phase helps give an early indication of whether a drug will be effective. It is designed to establish what test conditions will be needed in Phase III to ultimately demonstrate a treatment's effectiveness. By using drugs in various combinations of dosages, researchers decide on what the best dose and timing of the treatment will be for the final phase of testing. Phase II typically involves a relatively small number of patients and lasts about two years. Phase studies II may or may not involve a “control” group of patients who receive only a non-active “placebo”.

Phase III:

About 45% of drugs pass Phase II and move on to Phase III. In this phase, researchers compare the agent to the current standard of treatment or a placebo, an inactive ingredient. This phase lasts 1-4 years and will ultimately determine whether the treatment is effective. Depending on the disease studied, hundreds or even thousands of people may be enrolled. About 60% of drugs that enter Phase III are approved by the FDA. Overall, only 20% of drugs that enter clinical trials get final approval.

Double-Blind Studies

In a double-blind study, neither the participants who are enrolled nor their doctors are told which drug or treatment the participant is receiving. Double blind studies typically occur in Phase II and III trials.

Who Is Eligible for Clinical Trials?

Eligibility criteria for clinical trials are stringent so that scientists can measure results with fewer complicating factors, such as previous treatments or medications taken for unrelated conditions. But finding enough people who meet those requirements takes time. Often as long as 3-5 years.

Using the Internet to Recruit Participants

The National Institutes of Health (NIH) clinical trials website is a searchable database that aims to bring together scientists and potential trial participants. Patients, families, or physicians can easily hunt through more than 5,000 trials to find ongoing or completed research related to a specific condition. You can browse through a list of diseases or trial locations, or let the site narrow it down through a focused search.

"The goal is to have people come to one site," says Alexa T. McCray, PhD, director of biomedical communications for the National Library of Medicine. "People were having trouble finding the information they needed."

Presently the site contains mostly NIH-funded trials for serious or life-threatening conditions. Plans include adding other government and privately funded studies.

Participation in Clinical Trials Is Low

At any given time, Dr. McCray estimates that at least 15,000 trials are under way in the United States, yet experts say as few as 2%-5% of potential patients participate. In addition to lack of awareness, the cost of participating may be keeping potential candidates away. Insurers often will not pay for experimental treatments or standard, routine care administered during a trial. As a result, many trials, especially those of new drugs, provide free drugs and needed testing to participants.

Considering a Clinical Trial

Dr. McCray suggests you do the following when considering participating in a clinical trial:

  • Consult with your physician.
  • Review and fully understand everything contained in the informed consent, a document that outlines key facts and the potential benefits and risks.
  • Ask questions, such as:
    What procedures are involved?
    How long will the treatment take?
    How often must I go to the hospital or study site?
    What should I avoid while participating?
    Can I continue taking other prescription drugs during the trial?
    What will be expected of me overall?

Keep in mind that the medication or treatment being tested in a trial may have unexpected or unpleasant side effects. The regimen may also be complex and hard to follow. However, patients can withdraw at any time after enrolling.

A Positive Experience Overall

A recent Harris poll commissioned by the National Coalition for Cancer Survivorship (NCCS) and three other organizations found that people who have participated in trials considered it a positive experience. For some, it has meant life-saving treatments, and for others, vastly improved quality of life.

For cancer patients, trials are critical, says Ellen L. Stovall, executive director of the NCCS.

"The person treated for cancer, in randomized clinical trials, is going to get at least the standard of care," Stovall says. "Or they are going to get a treatment researchers believe may be better. There's very little downside."


AIDS Clinical Trials Information Service

Cancer Trials
National Cancer Institute

US Food and Drug Administration


BC Cancer Agency



Connolly NB, Schneider D, Hill AM. Improving enrollment in cancer clinical trials. Oncol Nurs Forum. 2004;31(3):610-4.

Joffe S, Weeks JC. Views of American oncologists about the purposes of clinical trials. J Natl Cancer Inst. 2002;94(24):1847-53.

Zivin JA. Understanding clinical trials. Scientific American. 2000:69-75.

Last reviewed March 2008 by Marcin Chwistek, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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