New medical treatments must be proven safe and effective before
they can be offered to a large number of patients. New
treatments are tested through clinical trials, a series of
research studies using a limited number of patients. Any new
type of treatment can be tested in a clinical trial. For
example, when doctors use a marrow or cord blood transplant to
treat a disease not usually treated with a transplant, that
transplant is usually done as part of a clinical trial. Many
transplant patients take part in clinical trials that test drugs
used prior to transplant or to stop infection or fight graft-
versus-host disease (GVHD) after transplant. Most patients who
receive an unrelated donor transplant have the option of taking
part in a clinical trial at some time during their treatment. If
you are thinking about being in a clinical trial, you should
learn all you can about the trial you are considering. You
should also learn about how clinical trials work. Clinical
trials phases There are three phases of clinica