Human epididymis protein 4 in cancer diagnostics: a promising and reliable tumor marker.

Human epididymis protein 4 (HE4) is a member of the "four-disulfide core" family that comprises a heterogeneous group of small acid- and heat-stable proteins of divergent function. Although there is an exponential growth of evidence that HE4 is a valuable tumor marker for ovarian malignancies, the exploration of the usefulness of this glycoprotein in the large tumor landscape is still ongoing. Enzyme-linked immunosorbent assay, chemiluminescent microparticle immunoassay, and bead-based array system are the preferred analytical methods for measuring HE4 concentration. Serum and urinary HE4 levels appear to be more affected by carcinogenesis than by other pathologic processes. Apart from the malignancy itself, histological type of cancer, cancer stage, and menopausal status affects HE4 concentration. An important objective in nowadays research remains the development of a tumor marker panel with a sufficient accuracy for risk assessment, early diagnosis, prognosis, and response to therapeutic treatment of cancer.