Potential clinical value of circulating chromogranin A in patients with prostate carcinoma

Background: Neuroendocrine (NE) differentiation of prostate adenocarcinoma has received increasing attention in recent years as a result of possible implications for prognosis and therapy. The presence of NE tumor subpopulation can be gauged non invasively by measuring circulating levels of secretory products, primarily chromogranin A (CgA). Methods: This article provides a review on published papers evaluating circulating CgA in prostate cancer patients. Results: Circulating CgA levels were found to be higher in prostate cancer patients than in patients with benign or premalignant prostatic diseases. In patients with malignancy, they correlated either to the stage of disease or to the condition of hormone refractoriness. CgA levels did not correlate with serum prostate specific antigen (PSA) and were supranormal in the majority of advanced patients with PSA within normality. In hormone refractory cases, elevated CgA was a significant predictor of poor prognosis, independently from serum PSA. CgA values were not substantially affected by either endocrine therapy or chemotherapy. They were found to increase during androgen deprivation in some cases and this trend preceded that of PSA. The administration of a somatostatin analog in hormone refractory cases was able to reduce plasma CgA values consistently. Conclusions: Present data suggest a potential role of circulating CgA in the management of prostate cancer patients. CgA determination may be useful diagnostically and prognostically and could offer complementary information with respect to PSA. Serial evaluation of circulating CgA could provide information on changes in the NE phenotype expression as a consequence of tumor progression and/or treatment administration.