Often researchers use standard therapy as the base to design new, hopefully better treatments. Then in Phase III, the new treatment is directly compared to the old one. In Phase IV studies, the new research treatment becomes part of standard treatment in patient care. This spells out what will be done and why. Studies are planned to safeguard the medical and psychological health of patients as well as to answer research questions.
Some clinical trials test one research treatment in one group of patients.
Other trials compare two or more treatments in separate groups of patients who are similar in certain ways such as the extent of their disease. This way, the treatment groups are alike, and the results from each can validly be compared. Sometimes, no standard treatment yet exists for certain cancer patients. In drug studies for such cases, one group of patients might receive a new drug and the control group, none. But no patient is placed in a control group without treatment if there is any known treatment that would benefit that patient.