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Treatment Clinical Trials: An Overview


 Clinical trials are research studies involving people. There are different types of clinical trials. For example, there are prevention, early detection and treatment clinical trials. Treatment clinical trials are the most common type of cancer clinical trial. Clinical trials occur in four phases, each with different objectives and numbers of participants. The four phases of treatment clinical trials are summarized below.

PHASE I: 15-30 patients

Phase I objectives are to determine safe dosages for a drug under study (a new drug or pre-existing drug used for a new purpose), how to administer the drug and observe its effects in patients.

PHASE II: Less than 100 patients

Phase II objectives are to determine if the drug under study has an anti-cancer effect and to observe its effects in patients.

PHASE III: Generally, 100 to 100s of patients

Phase III objectives are to compare the drug under study to the standard treatment available, i.e., some patients get the “new” drug while others get the “old” drug.

 PHASE IV: 100s to 1000s of patients

Phase IV objectives are to evaluate a drug’s long-term safety and effectiveness, usually after a drug is approved.

Modified from the National Cancer Institute’s “Cancer Clinical Trials–Types and Phases”, available online at cancer.gov.