Measuring the quality of care for the cancer patient. In recent years, the efforts to better define quality of patient care have focused on attempts to improve on the measurement of quality. These efforts raise three questions: (1) Why attempt to measure quality? (2) What is the best way to measure quality of care of the cancer patient? and (3) What must be done to achieve this? Three main reasons for measuring quality of patient care are to describe the current state, plan strategies for improvement, and implement and monitor improvements. To measure quality, both the definition of quality and the tools available for measurement must be addressed. The difficulty in developing a measurable definition of quality is achieving agreement on the measurable components of quality. The tools to measure quality have evolved to focus on monitoring of key indicators for comparative use. The utility of indicators lies in demonstrating that they have the capacity to identify opportunities for improving care. The Joint Commission is improving measurement tools through the development and testing of oncology indicators for reliability and the capacity to identify opportunities for improving care. The development and teaching of new quality improvement methods to health care professionals also is necessary. 