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Questions About Cancer? 1-800-4-CANCER

Learn About Clinical Trials

  • Reviewed: 12/29/2004

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People are asked to take or do something.

In some studies, people are asked to do something to lower cancer risk. For example:

  • Exercise
  • Follow a special diet.

In most studies, people are asked to take something to lower cancer risk. For example:

  • Take a medicine
  • Take a vitamin.

When people are asked to take something, it may be:

  • The standard agent: A medicine or vitamin that is already used to prevent a certain cancer
  • The study agent: A new medicine or vitamin that doctors hope will be better than what is already used to prevent a certain cancer
  • The placebo: A pill that has no medicine at all. It helps doctors figure out whether or not the study agent really works to prevent cancer.