TMUGS should help make order out of the chaos that exists in evaluation of tumor markers for clinical use. Although it seems cumbersome at first, application of this system by expert reviewers should help separate those markers for which clinical utility clearly exists from those markers for which either more data are necessary or for which further consideration can be discarded. Perhaps as important, this system may serve as a framework in which clinical and translational investigators can design studies prospectively to generate LOE I or II data, and thus hasten the acceptance of new biologic factors into routine clinical practice.