Trial information for patients

Questions you may have

What are clinical trials?
Why are clinical trials conducted?
What are the types of clinical trials?
How is the safety of clinical trial participants protected?

What are clinical trials?

Clinical trials are research studies that involve people. These studies test new ways to prevent, detect, diagnose, or treat diseases. People who take part in cancer clinical trials have an opportunity to contribute to scientists' knowledge about cancer and to potentially help in the development of improved cancer treatments. (1)

Why are clinical trials conducted?

Clinical trials look at new ways to prevent, detect or treat disease. Treatments might be new drugs or new combinations of drugs or new ways to use existing treatments. The goal of clinical trials is to determine if a new test or treatment works and is safe. Clinical trials can also look at other aspects of care, such as improving the quality of life for people with chronic illnesses. (2)

Once the drugs are proven to have an acceptable safety profile and proven to work, the Food and Drug Administration (FDA) and/or the European Medicines Agency (EMA) may approve them. The drugs then can be prescribed by doctors. Many treatments used today are the result of past clinical trials.

What are the types of clinical trials?

  Purpose   Number of Patients who take part
  Phase 1
  • To find a safe dose
  • To decide how the new treatment should be given
  • To see how the new treatment affects the human body

15-30 people

  Phase 2
  • To determine if the new treatment has an effect on a certain cancer
  • To see how the new treatment affects the human body

Fewer than 100 people

  Phase 3
  • To compare the new treatment (or new use of a treatment) with the current standard treatment

From 100 to several thousand people

  Phase 4
  • To further assess the long-term safety and effectiveness of a new treatment

Several hundred to several thousand people (3)

How is the safety of clinical trial participants protected?

National and international regulations and policies have been developed to help ensure that research involving people is conducted according to strict scientific and ethical principles. In these regulations and policies, people who participate in research are usually referred to as "human subjects."

Clinical trials are reviewed by the country's regulatory department. For example, in the US, clinical trials are reviewed by the U.S. Food and Drug Administration (FDA) and in Canada, that review is done by Health Canada.

In addition, each hospital that conducts a clinical trial must have the study reviewed and approved by an Institutional Review Board (IRB). The IRB reviews all aspects of a clinical trial to make sure that the rights, safety, and well-being of trial participants will be protected. The IRB must also review ongoing trials at least yearly and, based on those reviews, can decide whether the trial should continue as initially planned or if changes should be made to improve participant protection. An IRB can stop a clinical trial if the researchers are not following the protocol or if the trial appears to be causing unexpected harm to the study participants.

An IRB must have at least five members, including one scientist, one person who is not a scientist, and one person who is not affiliated with the institution where the trial is taking place and who is not an immediate family member of someone who is affiliated with that institution. The nonscientist and the nonaffiliated member can be the same person. IRBs can also include doctors, nurses, social workers, chaplains, patient advocates, and other health care or community professionals. All members of an IRB are required to be educated about the IRB's purpose, functions, and responsibilities, as outlined in federal regulations. Trials taking place at multiple locations can involve multiple IRBs.

Clinical trials also may use a Data and Safety Monitoring Board (DSMB) or a safety monitoring committee to monitor the safety and progress of the trials.

A DSMB is a committee of doctors, statisticians, and others who are independent of the people, organizations, and institutions that are sponsoring, organizing, and conducting the clinical trial. Similar to IRBs, DSMBs review the progress of a clinical trial and participant safety, but they also review data on the effectiveness of the trial interventions. DSMB members are experts in clinical research and clinical trials. They ensure that trial data are complete, and they can stop a trial early if safety concerns arise or if an answer to the main research question is obtained earlier than expected. Stopping a trial early because the main research question has been answered may make it possible for people who are not in the trial to get access to an effective intervention sooner. DSMBs have scheduled meetings to review clinical data, and their meeting minutes or recommendations are forwarded to the IRBs.(1)


  1. "Cancer Clinical Trials." National cancer institute, National Institutes of Health [learn more]
  2. "Clinical Trials, A chance to try new therapies." Mayo Clinic. The Mayo Clinic, 02 Jul 2011. Web. 10 Aug 2012. [learn more]
  3. National Cancer Institute, "Clinical trials take place in phases." Taking part in cancer treatment research studies. National Institutes of Health, 2007. Web. 10 Aug 2012. [learn more]
  4. "Joining A Clinical Trial. "MD Anderson Cancer Center. MD Anderson, n.d. Web. 10 Aug 2012. [learn more]

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