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Learn About Clinical Trials

  • Posted: 09/01/2011

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Clinical Trials Take Place in Phases

For a treatment to become standard, it must first go through 3 or 4 clinical trial phases. The early phases make sure the treatment is safe. Later phases show if it works better than the standard treatment. You do not have to take part in all phases.

 PurposeNumber of people who take part
Phase I
  • To find a safe dose
  • To decide how the new treatment should be given
  • To see how the new treatment affects the human body
15-30 people
Phase II
  • To determine if the new treatment has an effect on a certain cancer
  • To see how the new treatment affects the human body
Less than 100 people
Phase III
  • To compare the new treatment (or new use of a treatment) with the current standard treatment
From 100 to several thousand people
Phase IV
  • To further assess the long-term safety and effectiveness of a new treatment
Several hundred to several thousand people