Evaluating a New Marker’s Predictive Contribution

Abstract

One often begins the analysis of a new marker by first presenting its association or correlation with an established marker (e.g., tumor grade). For example, higher expression levels of the new marker in patients with high-grade tumors might be found. However, the value of an analysis like this is not clear. The results of this correlation analysis are not conclusive regarding the value of the new marker. For example, one would not want to see that a new marker correlated perfectly with an existing marker, as this would imply that the new marker was redundant. That is, equivalent predictions could be obtained by using an established marker. Unless the new marker is cheaper to measure than the established marker, or the new marker allows the patient to avoid a painful procedure (e.g., biopsy), correlation analysis provides little insight into the potential value of the new marker.