Clinical research is research done in humans. This research is a way for doctors and researchers to find new safe and effective treatments for diseases; find better ways to prevent, screen for, or diagnose diseases; find ways to improve quality of life for people with disease; or find ways to improve health care. Initial research on drugs or devices is usually done in the laboratory and then in animals prior to testing in humans. Research in humans, including those with breast cancer, is conducted in steps referred to as phases.

Phase I trials are the first step in testing a new treatment approach in humans. Safety is the main concern of these trials so patients are enrolled in small groups called cohorts. Phase I trials are designed to find a safe dose of the agent being studied. In cancer patients, these trials are usually done in patients with advanced or recurrent disease.

Phase II trials study the effectiveness of an agent or intervention. The safety profile of the agent or intervention is refined using information gathered in the conduct of this type of study. Phase II trials usually focus on specific type(s) of cancer and generally include less than 100 patients.

Phase III trials compare a new agent, intervention, or combination with current standard therapy and are usually based on results from phase I and phase II studies. Participants are randomly assigned (like a coin flip) to one of the treatment groups. Phase III trials generally include hundreds to thousands of people from across the US or the world.

Phase IV trials are conducted to further evaluate long-term safety and effectiveness of a treatment. They usually take place after the treatment has been approved for standard use and may include several hundred to several thousand participants.

Many of the medical and surgical treatments used today in fighting cancer are the result of what we learned through clinical research trials. Current clinical trials will help determine many of the tests to diagnose cancer earlier and the medications and surgical techniques that will be used to treat patients in the future.