Measure validation is an ongoing process: the Functional Assessment of Cancer Therapy-Breast Symptom Index as a case example

Patient-reported outcomes (PROs) such as measures of symptoms status or health-related quality of life (HRQL) have demonstrated their value to clinical practice and research over the last three decades. Routine assessment of HRQL has been shown to enhance clinical care by improving problem identification and management, patient-provider communication, and patient satisfaction with care (1-3).