The sine qua non of discovering novel biomarkers for early detection of ovarian cancer: carefully selected preclinical samples.

This perspective discusses reports by Cramer and colleagues (beginning on page 365 in this issue of the journal) and Zhu and colleagues (beginning on page 375), which provide the first systematic and reliable comparison of a large number of candidate biomarkers for the early detection of ovarian cancer in a sample set well-suited for this purpose. This research has important implications for the future design of cancer biomarker studies.