Recent advances in evaluating the prognostic value of a marker.

Predominately, the intended purpose of a new marker is to augment currently available knowledge about a disease process. That is, by combining the marker with existing knowledge, the researcher hopes to obtain a more accurate estimate of a patient's risk for a certain outcome. This estimate is a measure of absolute risk; for example, if the outcome is binary (such as whether or not metastatic disease is present within 5 years after tumor resection surgery), the absolute risk for a given patient would be the estimated probability of the outcome. Rather than evaluate the performance of absolute risk measures such as this, many marker studies unfortunately focus on measures of relative risk within a sample of patients. Examples of these relative measures include odds ratios for binary outcomes, hazard ratios for time-to-event outcomes, and differences in means for continuous outcomes.