The primary goal of outcomes research is to assess treatment effectiveness, or the positive impact that a given therapy has on aspects of care that are of interest to both patient and clinician. It is designed to identify the most effective form of treatment for cancer among the variety of treatment options. By combining cost analysis with a thorough calculation of treatment outcome according to the expanded definition, the physician and the patient obtain the most complete information regarding the treatment for head and neck cancer. Central to the task of outcome assessment is the definition of a clinically relevant outcome. In contrast to nonneoplastic processes, the usual outcome of an unsuccessful treatment in head and neck cancer is death from uncontrolled disease. Subsequently, the primary outcome measure used to assess treatment effectiveness has been survival. In modern outcomes research, the emphasis is broadened to encompass measures of outcome other than survival alone. This broader approach evaluates not only traditional end points, such as mortality and local control, but also other parameters, such as patient satisfaction, quality of life, functional status, and cost of care.