IMMUNOASSAY AND IMMUNOHISTOLOGY STUDIES OF CHROMOGRANIN-A AS A NEUROENDOCRINE MARKER IN PATIENTS WITH CARCINOMA OF THE PROSTATE

Objectives. Neuroendocrine differentiation in carcinoma of the prostat e is characterized by the expression of neuroendocrine cell products s uch as chromogranin A (CgA). We studied serum levels and tissue staini ng for CgA in prostate cancer to assess their clinical value. Methods. In 82 patients with prostate cancer, serum specimens were obtained at diagnosis and studied by both CgA and prostate-specific antigen (PSA) immunoassays. In 43 additional patients with prostate cancer, paraffi n-embedded tissue from core biopsies or transurethral resections and s erum samples were studied, respectively, by immunohistology and immuno assay for CgA. Results. In serum samples from the 82 patients in whom CgA and PSA levels were measured, 26 of 82 (32%) had an elevated CgA ( greater than 200 ng/mL), and 36 of 82 (44%) had an elevated PSA (great er than 4.0 ng/mL). Of the patients with Stage D2 cancer, 11 of 18 (61 %) had an elevated CgA and 6 of 18 (33%) had an elevated PSA. Four of 5 patients with local recurrence had an elevated CgA, but only 1 patie nt had an elevated PSA. Of the 45 patients in whom serum and tissue Cg A studies were performed, 12 (28%) had elevated serum CgA, and 15 of t he 45 (35%) had CgA staining in their prostate tissue. Of the 14 of th ese patients with D2 disease (distant metastases), 9 (64%) had elevate d serum levels of CgA and 6 (43%) had positive staining in their prost ate tissue. Of the 9 patients with Stage D2-disease and elevated serum CgA, 6 had a normal serum PSA. Conclusions. Our studies complement th ose of others and indicate-that CgA has potential as a clinically usef ul serum and tumor marker for prostate cancer. Serum CgA measurements can identify some patients with advanced disease who do not have eleva ted serum PSA. However, further studies in larger groups of patients a re needed to define the clinical value of CgA as a marker for prostate cancer.