PRO data is information about patient experienced symptoms, functional capacity, and quality of life and has not yet been implemented as a systemically obtained measurement in the follow-up program. According to the US Food and Drug Administration (FDA) PRO data is: "any report of the status of a patient's health condition that comes directly from the patient, without interpretation of the patient's response by a clinician or anyone else". PRO data are typically collected through a questionnaire in which measurements are repeated over time. This allows continuous monitoring of the patient health status. PRO data is a tool to improve healthcare quality and the key to organize and deliver healthcare in a way beneficial to the patients. Today, PRO data are not routinely obtained during follow-up, but the new guidelines from the Danish Health and Medicines Authority recommend the use of PRO data. The implementation faces several challenges due to the extra effort by the staff, the development of appropriate electronic equipment, and determination of the proper use in different parts of the healthcare system.