Quality-of-life outcomes in oncology

Quality of life (QOL) endpoints are assuming an increasing role in clinical oncology trials. This article reviews the definition of QOL and the importance of measuring QOL in oncology trials. The optimal choice, timing, and frequency of QOL instruments are summarized. Methodologic issues are also reviewed, including the statistical interpretation of QOL data. Finally, the Radiation Therapy Oncology Group clinical outcomes triad model is described. Future QOL studies must focus on randomized trials with clear hypotheses that can lead to clinically meaningful interventions.