Clinical trials are research studies that use human patients to determine if a new treatment is effective. Medical and ethical panels overseen by the Food and Drug Administration (FDA) carefully review the research methods and ethics of a clinical trial before the trial begins, then monitor the trial throughout its four main phases.
Phase I of a clinical trial studies a small number of patients to determine the best dosage and delivery method of a new drug treatment. Patients who participate in a Phase I trial usually have advanced cancer and would not be helped by other known treatments. Phase II, conducted with a different group of patients, determines how well the treatment actually works in different types of cancer. Phase III compares the effectiveness of the new treatment in one set of patients to another set of patients who receive the best currently available drug treatment. In Phase IV studies, the treatment becomes part of the standard treatment regimen, but it is tested for how effective it is when combined with other treatments.
Researchers continually study and find new ways to treat cancer. Studies in an area of research called antimetastasis focus on halting tumor cells from spreading and invading new tissues. Other researchers study how to stop a tumor from developing its own blood supply, a process called antiangiogenesis. Two antiangiogenesis drugs, called angiostatin and endostatin, stop the growth of blood vessels and have been quite successful in treating tumors in mice. These two drugs are currently in clinical trials in humans.
Several drugs that block oncogene signals are in clinical trials. Researchers are also introducing genes into immune cells that will specifically recognize and kill cancer cells. Other research is investigating the introduction of a normal gene into a tumor cell to increase the tumor's sensitivity to chemotherapeutic drugs.
A growing field of cancer prevention research is chemoprevention, or the use of natural or synthetic compounds to decrease the number of mutations that may lead to cancer. Chemoprevention research seeks to identify those compounds that reduce risk and use them in pills or food additives as a prevention measure for those who are at high risk for cancer. More than two dozen chemopreventive compounds are currently being studied for how well they work in humans.