Comparison between two commercially available chromogranin A assays in detecting neuroendocrine differentiation in prostate cancer and benign prostate hyperplasia

BackgroundChromogranin A (CgA) is the neuroendocrine (NE) marker most frequently employed in detecting NE differentiation in prostate cancer patients, either at the tissue level or in the general circulation.MethodsWe compared the two commercially CgA assay kits in detecting NE differentiation, in benign hyperplasia (BPH) or prostate cancer (PC) patients (pts). 170 pts with BPH, 107 with BPH + inflammation, and 136 PC pts entered the study. CgA was measured in each patient with the immunoradiometric assay (IRMA) and with the enzyme-linked immunoabsorbent assay (ELISA).ResultsA moderate relationship was found between CgA measured with IRMA and ELISA in the whole population (Spearman's R = 0.65, p < 0.05), in BPH pts (R = 0.76, p < 0.05), in BPH + inflammation pts (R = 0.53, p < 0.05) and in PC pts (R = 0.60, p < 0.05). Twenty-two out of 62 pts (35.4%) with elevated ELISA CgA did not have increased IRMA CgA; by contrast, 21/61 pts (34.4%) with elevated IRMA CgA were not recognized as abnormal by the ELISA kit.ConclusionsCgA measured by the two assays provided a significant discordance rate, suggesting that the two kits might elicit different information.