Clinical trials, also called clinical studies, test new methods to treat, diagnose and prevent cancer. Only treatments that provide promising results in laboratory tests advance to clinical trials.
Phase I trials are the first step at testing new treatments in people. They help researchers determine the best way to administer a new treatment and the appropriate dosage. These trials also establish whether a treatment has any potentially harmful side effects. Phase 1 trials involve a small number of people.
Phase II trials focus on learning whether a new treatment can shrink a tumor, improve blood test results or provide other desirable effects. There are usually involving fewer than 100 participants.
Phase III trials compare the new treatment to the best existing treatment for a particular type of cancer. Many patients — from the hundreds to even the thousands — receive either the new treatment or the best existing treatment. A Phase III trial may involve adding a new drug to an already-proven combination of drugs to see if the new combination is more effective.
For a more complete description of how clinical trials are structured, see our paper Participating in a Prostate Cancer Clinical Trial.
To Learn More About Clinical Trials
The National Cancer Institute provides a Clinical Studies Support Center in Bethesda, Maryland. You can talk with an Information Specialist by calling 1-888-NCI-1937 between 9:00am and 5:00pm Eastern Time, Monday – Friday. You may also contact the PCRI Helpline.