Why test new treatments?

When researchers think that they have found a promising treatment they do not immediately treat patients with it. If it is a brand new treatment, they will first test it in the laboratory, usually on tumor cells. If results in the laboratory are encouraging, they will test the treatment on animals. These studies are highly regulated to avoid unethical tests on animals. If results of the tests on animals are encouraging, researchers will set up, together with doctors, the first step of the experimentation of the new treatment on humans. This first step in humans is called a phase I clinical trial. Phase II and phase III clinical trials will follow if results are encouraging during the previous step. Thus, the risk for participants is higher in phase I than in phase II, and risks of a phase II trial will be higher than in phase III.

Sometimes, the treatment tested is not new, but the way it is given, the dosage or the combination with other treatments differ. It may also be a treatment already used for one type of cancer. Before using it for another type of cancer, however, a new study has to be done to see whether the treatment is safe and works for the new type of cancer.