Plasma chromogranin A as marker for survival in patients with metastatic endocrine gastroenteropancreatic tumors - Arnold, R; Wilke, A; Rinke, A; Mayer, C; Kann, P H; Klose, K J; Scherag, A; Hahmann, M; Müller, H H; Barth, P (Clin Gastroenterol Hepatol, 2008)