Serum efficacy biomarkers for oncology.

Considerable interest has emerged in serum biomarkers that can be used to evaluate early effects of cancer therapeutics. Such efficacy biomarkers are expected to become valuable both for routine clinical care and for anticancer drug development. Here, we review the literature on serum efficacy biomarkers. We discuss how data using such markers can be interpreted, particularly with regard to the issue of specificity of different markers. An important question is whether biomarker response evaluation is expected to be congruent with evaluation by traditional anatomical methods. We argue that they may not be - biomarkers are expected to provide information with regard to induction of tumor cell death that will not necessarily reflect clinical outcome.