Phase I trials test new treatments for safety in humans and any harmful
side effects. These studies usually include a limited number of patients who
would not be helped by other known treatments
Phase II trials determine whether the new treatment is effective against
specific tumors. A small number of people participate because risks and benefits
are largely unknown.
Phase III trials compare the result of people taking the new treatment
with results of people taking standard treatment. Phase III testing occurs only
when a protocol shows promise in Phases I and II. Phase III trials may include
hundreds of people around the country.