Clinical trials are typically conducted in three to four steps or phases. Knowing the clinical trial phase can tell you how much is known about the treatment and the potential benefits and risks.

• Phase I trials: Doctors are testing if a new treatment is safe in people. They are looking to identify the highest dose that can be given without causing severe side effects. Phase I trials carry the most potential risk but can benefit patients with high-risk or treatment-resistant cancer.
• Phase II trials: At this phase, doctors test many patients with a specific type of cancer to see if they respond to the new treatment. Usually, less common side effects are uncovered during this phase due to the larger group of patients receiving the new treatment.
• Phase III trials: This phase is used to compare the safety and effectiveness of the new treatment against the current approved treatments.
• Phase IV trials: After the FDA approves the new treatment, it may be watched over a long period of time in a phase IV trial. The purpose of this phase is to find more information about long-term benefits and side effects. This step is often the safest for patients since the treatment has already been studied during previous phases.