Biomarkers have been the mainstay in the diagnosis and follow-up of patients with neuroendocrine tumors (NETs) over the last few decades. In the beginning, secretory products from a variety of subtypes of NETs were regarded as biomarkers to follow during diagnosis and treatment: serotonin for small intestinal (SI) NETs, and gastrin and insulin for pancreatic NETs. However, it became evident that a large number of NETs were so-called nonfunctioning tumors without secreting substances that caused hormone-related symptoms. Therefore, it was necessary to develop so-called “general tumor markers.” The most important ones so far have been chromogranin A and neuron-specific enolase (NSE). Chromogranin A is the most important general biomarker for most NETs with a sensitivity and specificity somewhere between 60 and 90%. NSE has been a relevant biomarker for patients with high-grade tumors, particularly lung and gastrointestinal tract tumors. Serotonin and the breakdown product urinary 5-hydroxyindoleacetic acid (U-5-HIAA) is still an important marker for diagnosing and follow-up of SI NETs. Recently, 5-HIAA in plasma has been analyzed by high-performance liquid chromatography and fluorometric detection and has shown good agreement with U-5-HIAA analysis. In the future, we will see new tests including circulating tumor cells, circulating DNA and mRNA. Recently, a NET test has been developed analyzing gene transcripts in circulating blood. Preliminary data indicate high sensitivity and specificity for NETs. However, its precise role has to be validated in prospective randomized controlled trials which are ongoing right now.
The strong association of the presence of a fibrotic focus with CA9 expression and lower survival demonstrates that hypoxia-driven angiogenesis plays an important role in the progression of PA.
The influences ofmultiple endocrine neoplasia type 1 (MEN 1), hypergastrinaemia, age, and sex on gastric endocrine cell densities were studied in 48 patients with the ZollingerEllison syndrome of either the sporadic type (n=31) or associated with MEN 1 (n= 17). The mean fundic argyrophil cell density was higher in women (p<005). It showed no appreciable difference between young and old women but it declined with age in men. The mean argyrophil cell density, when adjusted for sex, was higher (+48.5%, p=006) in patients with ZollingerEllison syndrome associated with MEN 1 than in those with sporadic type disease. This measurement was not significantly different between the two groups of patients when antisecretory treatments were considered. In patients with sporadic type disease, fundic argyrophil cells showed a normal pattern (16%) or diffuse (71%) or linear (13%) hyperplasia. In patients with MEN 1 diffuse and linear hyperplasia were of the same order (53% and 47%). Furthermore, fundic argyrophil endocrine tumours developed in five of 17 -that is, 29.5% of patients with associated MEN 1 while none was seen in patients with sporadic type disease. These tumours showed an exclusive or prominent enterochromaffin like cell population. Antral gastrin and somatostatin cell densities and fasting serum gastrin concentrations were similar in the two groups of patients with Zollinger-Ellison syndrome. Whatever the underlying mechanism for carcinoidosis, the risk of developing fundic enterochromaffin like cell tumours in Zollinger-Ellison syndrome patients who present with MEN 1 is probably higher than was initially estimated and suggests that regular follow up of these patients is necessary.
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