Study Doctors and other researchers want study participants to be safe and healthy. However, they have other interests as well.
For example, occasionally a Study Doctor may have a direct or indirect financial interest in the outcome of the study. A Study Doctor may own stock in the company that is testing a new medicine, or may receive money for providing services to a company that makes a medical device. Depending on how much of a financial relationship investigators have with a company, they may benefit if the study finds the new treatment to be effective, and the company then makes a profit on the treatment.
Sometimes the various interests that a doctor has may be in conflict with each other. This is known as a "conflict of interest."
You can ask about conflict of interest policies at the location where the research is taking place. You can also talk to the Study Doctor or other members of the research team about their interests in this study. If you feel there is the potential for a conflict of interest, you may also ask to talk to a physician who isn't one of the investigators.