Despite the plethora of reports on tumor markers in oncology, the number of markers that have emerged as clinically useful is disappointing. There is considerable evidence that the quality of reporting of studies of biomarkers, particularly tumor prognostic markers, is generally poor. McShaneet al. present guidelines that provide helpful suggestions on study design, patient characteristics, statistical analysis methods, and guidance on how to present data. The authors advocate the importance of transparent and complete reporting of tumor marker prognostic studies in order to increase accessibility and interpretability of trial data, which should help to improve patient treatment and management.