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What is a Clinical Trial?

Clinical trials are research studies that involve people. They are the final step in a years-long process that begins with research in a lab and animal testing. Many treatments used today are the result of past clinical trials.

Clinical cancer trials are designed to answer questions about new treatments or new ways of using an old treatment and how well they work. These trials may test drugs or vaccines, ways to do surgery or give radiation therapy or combinations of many treatments. Your doctor may offer you the option to join a clinical trial as part of your treatment plan.

Clinical cancer trials follow very strict rules, called protocols, that are overseen by a governing scientific and ethical body. The protocol will determine who can participate in the trial and help make sure the trial is safe and has accurate and meaningful results.

Why Participate in a Clinical Trial?

Deciding to participate in a clinical trial is not an easy decision. However, for many CU Cancer Center cancer patients clinical trials are often the best course of treatment. While there are many benefits and risks to clinical trials, these studies help discover new treatments for future cancer patients.


    • Gain access to latest available treatments.
    • Obtain expert medical care at CU Cancer Center clinical trial sites.
    • Help future cancer patients and allows you to take an active role in your treatment options.
    • Trial sponsors may pay for some of your medical care.


    • Specific risks and effects will be outlined for each trial and they can vary.
    • Side effects could be worse than those of standard treatment.
    • The new treatment may not turn out better than standard treatment or it may not work for you, even if it worked for other patients.
    • The trial may require more of your time than traditional treatment would.

Clinical Trial Phases

Cancer treatments are tested in three to four phases before they become standard treatment. Each phase of testing seeks answers to specific questions.

Phase I

  • How does the new treatment affect the human body?
  • How should the new treatment be given?
  • What is the safe dose for the new treatment?
  • About 15-30 people participate
  • CU Cancer Center is the only place in Colorado that offers Phase I trials

Phase II

  • Does the new treatment affect a certain cancer?
  • How does the new treatment affect the human body?
  • Fewer than 100 people participate
  • CU Cancer Center has more Phase II trials than any other center in the region

Phase III

  • How does the new treatment compare to the current or standard treatment?
  • 100 to thousands of people participate

Phase IV

  • How safe and effective is the new treatment in the long term?
  • Several hundred to thousands of people participate

For more information about participating in clinical research trials, please read the NCI online booklet, Taking Part in Cancer Treatment Research Studies.

Who Can Participate in a Clinical Trial?

Every University of Colorado Cancer Center clinical trial has its own eligibility requirements. Criteria often include age, gender, type and stage of disease, previous treatment history and other medical conditions.

Search the CU Cancer Center Clinical Trial Database to see if you quality for any studies.