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UC Davis Comprehensive Cancer Center

UC Davis Comprehensive Cancer Center

What are cancer clinical trials?

clinical trials

A cancer clinical trial is designed to answer a specific question.  For example: Is a promising investigational drug effective?  Does a newly approved drug work even better with an older drug?  Which is more effective, chemotherapy followed by surgery, or surgery followed by chemotherapy?



How are clinical trials carried out?

Cancer clinical trials are carried out in phases:

  • Phase I trials evaluate how a new drug should be given, how often and at what dose.  A Phase I trial usually enrolls a small number of patients.
  • Phase II trials test how effective a new drug or procedure is against a particular cancer.
  • Phase III trials compare a promising new drug, new combination of drugs or new procedure with the best standard treatment.  Phase III trials typically involve large numbers of patients, usually hundreds or thousands.  A patient in a Phase III trial is randomly assigned to receive either the new treatment or the best existing treatment.
  • Phase IV trials ask new questions about standard treatments. A Phase IV trial might test how a newly approved drug works together with other effective drugs, or with surgery and/or radiation therapy.

In a cancer clinical trial, no patient goes without treatment if there is any known treatment that could benefit that patient. If it becomes clear during a clinical trial that one treatment is better than another, the trial is stopped and all patients in the trial are offered the more effective treatment. A trial will also be stopped early if an experimental treatment is found to be ineffective or harmful.


How is patient safety protected?

The doctors and nurses who are in charge of a clinical trial follow a carefully designed treatment plan known as a protocol. The protocol spells out exactly what and why certain procedures will be done, at what intervals, and how patients will be protected by close monitoring.

At UC Davis, every protocol must be approved by the University’s Institutional Review Board (IRB), which is made up of scientists, non-scientists, members of our community, and representatives of special groups of subjects.  This ensures a complete and comprehensive review.  The IRB reviews each study for patient safeguards and scientific merit, and will continue to monitor the study throughout the life of the study.   The IRB will carefully consider whether the potential risks of a trial are reasonable in relation to the potential benefits.  In addition, our cancer clinical trials are reviewed and monitored by the National Cancer Institute, the Southwest Oncology Group and other sponsoring organizations and government agencies such as the U.S. Food and Drug Administration and the Office for Human Research Protection.


Additional Resources

The National Cancer Institute and National Institutes of Health offer information about cancer clinical trials at the following Web sites:

You can also get information about clinical trials by calling the National Cancer Institute's Cancer Information Service at (800) 4-CANCER.