Recently, many cancer drugs have been approved by regulatory agencies based on single-arm studies, where analysis of quality of life (QoL) and patient-reported outcomes (PROs) is not a direct comparison with the standard, but the simple description of changes versus baseline and trends over time. This analysis can be potentially biased by missing data: QoL level could be overestimated, and symptoms underestimated. Caution is needed to avoid that a methodologically weak evidence in PROs and QoL data is overrated, if not for the drug approval, for the interpretation of data by scientific community and the communication with patients. PROs experts should be involved in planning, conduction, and interpretation of analyses.
Keywords: Patient-reported outcomes; clinical trials; methodology; quality of life; single arm trials.