The patient's perspective evaluated by patient-reported outcomes (PROs) gains more and more importance, since treatment efficacy is no longer solely linked to clinical outcomes like cure and overall survival. Ailments like pain, fatigue and social isolation can only be assessed by patients' direct expression without any interpretation made by medical staff. PROs facilitate the disclosure of quality of life issues and patients feel a stronger support due to improved communication. PROs offer many further advantages like saving of time, cost and staff, targeted intervention and sensitizing of clinicians. Also, internationally validated questionnaires are available and the development of electronic PROs eases data-collection, calculation and storage. PROs collected within clinical routine are versatile concerning their applicability: They can be used for scientific analyses, quality assurance, and health technology assessment.