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How Is a Clinical Trial Planned and Carried Out?
    Posted: 01/10/2001    Reviewed: 04/04/2008
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What Is a Clinical Trial?

Should I Take Part in a Clinical Trial?

How Do I Take Part in a Clinical Trial?

Participating in a Trial: Questions to Ask

In order to make a decision about whether to participate in a clinical trial, it helps to understand more about how trials are conceived and run. You will also want to know what happens when a trial is over.

Where do the ideas for trials come from?

The ideas for clinical trials often originate in the laboratory. Researchers develop a clinical trial protocol (the plan for a trial) after laboratory studies indicate the promise of a new drug or procedure. The first trials of a particular drug or procedure are focused on safety (phase I), and later trials focus on whether the drug or procedure is effective (phase II or phase III).

What is a protocol?

Every trial has a person in charge, usually a doctor, who is called the protocol chair or principal investigator. Phase I and phase II studies generally refer to the person in charge as the principal investigator. Phase III studies generally have a protocol chair, under whose direction multiple principal investigators carry out the protocol in participating sites. The protocol chair or principal investigator prepares a plan for the study, called a protocol. The protocol explains what the study will do, how it will be carried out, and why each part of the study is necessary. For example, the protocol includes

  • the reason for doing the study
  • how many people will be in the study
  • who is eligible to participate in the study
  • what study drugs participants will take, if any
  • what medical tests they will have, if any, and how often
  • what information will be gathered

Every doctor or research center that takes part in the trial uses the same protocol. This ensures that patients are treated identically no matter where or if they are receiving treatment, and that information from all the participating centers (if there is more than one) can be combined and compared.

Who sponsors clinical trials?

Clinical trials are sponsored by organizations or individuals who are seeking better treatments for cancer or better ways to prevent or detect cancer.

Individual physicians at cancer centers and other medical institutions can sponsor clinical trials themselves.

The National Cancer Institute (NCI) sponsors a large number of clinical trials. The NCI has a number of programs designed to make clinical trials widely available in the United States. Thousands of investigators at over a thousand sites participate in various aspects of NCI's clinical trials programs. These include the following.

  • Cancer Centers Program: About 60 research-oriented institutions have been designated as an NCI Comprehensive or Clinical Cancer Center for their scientific excellence. The centers are key partners in the NCI's efforts to bring the benefits of clinical research directly to you. Located throughout the country, they play an important role in cancer research, delivery of the highest quality cancer care, and outreach and education for the public and professionals.

  • Clinical Trials Cooperative Group Program: This program brings together groups of researchers, cancer centers, and community physicians into a national NCI-supported network. The network consists of a number of Cooperative Groups that seek to define the key unanswered questions in cancer and then conduct high-quality clinical trials at many sites around the country to answer these questions. The Cooperative Groups enroll about 20,000 new patients in treatment trials each year. Important III trials run by the Cooperative Groups help establish the state-of-the-art for cancer therapy. Additionally, the Groups perform large cancer prevention trials.

    • All clinical trials conducted by the Cooperative Groups are listed in NCI's registry of clinical trials. To search for trials sponsored by one or more of the groups, use the Lead Organization or Cooperative Group field at the bottom of the registry's advanced search form to browse an alphabetical list. (For further guidance, see Help Using the Advanced Clinical Trial Search Form.)

  • The Community Clinical Oncology Program (CCOP). This program makes clinical trials available in a large number of local communities in the United States by linking community physicians with researchers in cancer centers. Local hospitals throughout the country affiliate with a cancer center or a cooperative group. This enables doctors to offer people participation in clinical trials more easily, without having to travel long distances or leave their usual caregivers. Several of these programs focus on encouraging minority populations to participate in trials.

Drug companies or companies that make diagnostic equipment (like X-ray machines) sponsor trials of their products, hoping to demonstrate that their products are safe and effective. The U.S. Food and Drug Administration (FDA) will only permit companies to sell a product after it has been proven safe and effective in clinical trials. For more information, see

What happens when a clinical trial is over?

After a phase I or phase II trial is completed, the researchers look carefully at the data collected during the trial and decide whether to

  • move on to the next trial with the treatment, or
  • stop testing the treatment because it is not safe or effective

When a phase III trial comes to an end, the researchers must look at the data and decide if the results have medical importance. When the analysis of a phase I, phase II, or phase III trial is complete, the researchers will inform the medical community and the public of the study results.

In most cases, the results of trials are published in scientific or medical journals. To find out if the results of a study you participated in was published,

  • ask the doctor or nurse in charge of your treatment.
  • find out the official name of your study and search for the study in the PubMed database of medical publications. If you have trouble locating the study or searching for it, the research librarian at a university or medical library may be able to help.
  • use the advanced search form to search for the trial among the closed protocols listed in NCI's registry of clinical trials (change the status of the trial from "active" to "closed" on the advanced search form). Thousands of closed protocols have reference citations for published results.

Most medical and scientific journals have in place a process of peer review, in which experts critique the report before it is published, to make sure that the analysis and conclusions are sound. Particularly important results are likely to be featured by the print or electronic media, and widely discussed at scientific meetings and by patient advocacy groups. Once an intervention is proven safe and effective in a clinical trial, it may become the new standard of practice. In this way the development of better interventions for prevention, for treatment, or for detection and diagnosis is an ongoing, continuous process that builds progressively on itself to improve the quality of cancer care and prevention available to us all.

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