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.
Phase I
Purpose:
- To find a safe dose
- To decide how the new treatment should be given
- To see how the new treatment affects the human body
Number of people who take part:
Phase II
Purpose:
- To determine if the new treatment has an effect on a certain cancer
- To see how the new treatment affects the human body
Number of people who take part:
Phase III
Purpose:
- To compare the new treatment (or new use of a treatment) with the current standard treatment
Number of people who take part:
- From 100 to several thousand people
Phase IV
Purpose:
- To further assess the long-term safety and effectiveness of a new treatment
Number of people who take part:
- Several hundred to several thousand people
Adapted from National Cancer Institute
