The involvement of E-selectin in cancer has long been recognized based on histopathological studies, and the important role of E-selectin in cancer progression and metastasis was further reinforced by a number of basic researches. Both the solid state and soluble forms of E-selectin have been tested as a possible biomarker for different cancer types for detection as well as for monitoring. While a number of studies have suggested the potential usefulness of E-selectin as a biomarker, the results from clinical trials are somewhat controversial and it has not been translated into clinical utility. It appears that the use of E-selectin as a single biomarker for diagnosis and prognosis may require more careful evaluation. The utility of E-selectin as a biomarker in conjunction with other biomarkers that are relevant to the biological cascade for E-selectin or are critical for patient prognosis may open up a new venue to further establish E-selectin as a cancer biomarker.