Quality of life in oncology trials: a clinical guide.

Over the last 2 decades, there has been an explosion of quality of life (QOL) studies in the oncology literature. The purpose of this review is to provide a basic guide regarding the state-of-the-art of QOL in oncology trials from a clinical perspective. This article aims to provide fundamental definitions, describe useful existing tools, and highlight the challenges in interpreting QOL studies. What exactly is QOL, and why is it important to measure in cancer trials? Key methodological issues will be addressed, including choosing the optimal instrument, basic psychometric properties, timing of QOL assessments, and statistical considerations, such as minimizing missing data. The critical issue of interpreting the clinical significance of QOL results will be explored, using both anchor- and distribution-based strategies. The Radiation Therapy Oncology Group (RTOG) model involving a triad of outcomes (clinical, humanistic/QOL, and economic) will also be described. The future challenge will be to translate QOL results into clinically meaningful interventions.