Figure 2.For up to 9.2 years patients may present with a variety of symptoms including abdominal pain and are diagnoses as irritable bowel. Perhaps the earliest biomarker is Chromogranin A. The tumor continues to grow and metastasize and produce the constellation of clinical features of carcinoid syndrome. Quantifying pancreastatin is a marker of tumor growth as well as a means of monitoring successful reduction in tumor bulk with therapy. Neurokinin levels are a good marker for prediction of long term survival.