Types of Clinical Trials

There are two types of clinical research trials, therapeutic and non-therapeutic.

Therapeutic trials enroll patients and provide a specific treatment to the patients to study the impact on cancer.
Non-therapeutic trials do not provide a treatment to patients, but instead study important factors that help advance the understanding of cancer and its impact.

Within therapeutic trials, there are three different phases used to evaluate new treatments:

Phase I studies are the most basic of clinical trials. The evaluation of drug dosages and frequency of drug administration determine the MTD (Maximum Tolerated Dosages). The enrollment of patients with a variety of diseases is important to the study to determine effectiveness. Drugs are given at gradually increasing dosages until there are unacceptable side effects (dose-limited toxicities, DLT).
Phase II studies use the results from Phase I studies regarding MTD and DLT. The treatment targets a population of patients who responded most favorably in Phase I trials.
Phase III studies are those that most children will receive when newly diagnosed. These studies will test the standard treatment (current best) against promising alternatives that may increase cure rates or decrease side effects or late effects of treatment.