There are strict guidelines in place to ensure that clinical trial participants will be treated fairly and ethically, the same as if you were not on a trial. Before a test treatment is given to people who volunteer on clinical trials, it undergoes extensive screening, which can take many years to complete.
Every clinical trial also has an informed consent process, which will help you understand your rights as a participant on a clinical trial, including your right to leave the trial at any time if you no longer want to participate.