PURPOSE: Patient-reported outcomes (PROs), routinely collected as a part of cancer clinical trials, have been linked with survival in numerous clinical studies, but a comprehensive critical review has not been reported. This study systematically assessed the impact of PROs on patient survival after a cancer diagnosis within the context of clinical trials. DESIGN: Cancer clinical trials that assessed baseline PROs and mortality were identified through MEDLINE (through December 2006) supplemented by the Cochrane database, American Society of Clinical Oncology/European Society for Medical Oncology abstracts and hand searches. Inclusion criteria were publication in English language and use of multivariate analyses of PROs that controlled for one or more clinical factors. Two raters reviewed each study, abstracted data, and assessed study quality; two additional raters verified abstractions. RESULTS: In 36 of 39 studies (N = 13,874), at least one PRO was significantly associated with survival (P < .05) in multivariate analysis, with varying effect sizes. Studies of lung (n = 12) and breast cancer (n = 8) were most prevalent. The most commonly assessed PRO was quality of life, measured by the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire C30 in 56% of studies. Clinical variables adjusted for included performance status (PS), treatment arm, stage, weight loss, and serum markers. Results indicated that PROs provide distinct prognostic information beyond standard clinical measures in cancer clinical trials. CONCLUSION: PROs might be considered for stratification purposes in future trials, as they were often better predictors of survival than PS. Studies are needed to determine whether interventions that improve PROs also increase survival and to identify explanatory mechanisms through which PROs relate to survival.