Development of an ELISA for the detection of serum chromogranin A (CgA) in prostate and non-neuroendocrine carcinomas

Introduction: Chromogranin A (CgA) is a glycoprotein found in neuroendocrine cells and may be useful as a tumor marker for neuroendocrine tumors. Methods: We developed an enzyme-linked immunosorbent assay (ELISA) for serum CgA on a microtiter plate. Results: We established a reference range for both women and men of different age groups ranging from 20 to 80 years. Men appeared to have a slightly higher serum CgA concentration than women. This slight increase in serum CgA concentration was also found in both gender groups with advancing age. We also detected increased serum CgA in a variety of cancers and non-endocrine carcinomas: the majority of the increased serum CgA was associated with specimens containing highly increased concentration of tumor markers. In other words, increased serum CgA was found at later, more advanced stages of the disease in these patients. For patients with prostate cancer, serum CgA was increased much earlier than serum PSA in approximately one-third of prostate cancer patients developing resistance to hormonal therapy. Conclusions: The early rise of serum CgA provides an early signal for prostate cancer patients who developed resistance to hormonal therapy: this advance signal could create a critical window for therapy changes to be made before diseases progress to a fatal stage.