Chromogranin A as serum marker for neuroendocrine neoplasia: comparison with neuron-specific enolase and the alpha-subunit of glycoprotein hormones

Chromogranin A (CgA) is gaining acceptance as a serum marker of neuroendocrine tumors. Its specificity in differentiating between neuroendocrine and nonneuroendocrine tumors, its sensitivity to detect small tumors, and its clinical value, compared with other neuroendocrine markers, have not clearly been defined, however. The objectives of this study were to evaluate the clinical usefulness of CgA as neuroendocrine serum marker. Serum levels of CgA, neuron-specific enolase (NSE), and the alpha-subunit of glycoprotein hormones (alpha-SU) were determined in 211 patients with neuroendocrine tumors and 180 control subjects with nonendocrine tumors. The concentrations of CgA, NSE, and alpha-SU were elevated in 50%, 43%, and 24% of patients with neuroendocrine tumors, respectively. Serum CgA was most frequently increased in subjects with gastrinomas (100%), pheochromocytomas (89%), carcinoid tumors (80%), nonfunctioning tumors of the endocrine pancreas (69%), and medullary thyroid carcinomas (50%). The highest levels were observed in subjects with carcinoid tumors. NSE was most frequently elevated in patients with small cell lung carcinoma (74%), and alpha-SU was most frequently elevated in patients with carcinoid tumors (39%). Most subjects with elevated alpha-SU levels also had elevated CgA concentrations. A significant positive relationship was demonstrated between the tumor load and serum CgA levels (P < 0.01, by chi 2 test). Elevated concentrations of CgA, NSE, and alpha-SU were present in, respectively, 7%, 35%, and 15% of control subjects. Markedly elevated serum levels of CgA, exceeding 300 micrograms/L, were observed in only 2% of control patients (n = 3) compared to 40% of patients with neuroendocrine tumors (n = 76). We conclude that CgA is the best general neuroendocrine serum marker available. It has the highest specificity for the detection of neuroendocrine tumors compared to the other neuroendocrine markers, NSE and alpha-SU. Elevated levels are strongly correlated with tumor volume; therefore, small tumors may go undetected. Although its specificity cannot compete with that of the specific hormonal secretion products of most neuroendocrine tumors, it can have useful clinical applications in subjects with neuroendocrine tumors for whom either no marker is available or the marker is inconvenient for routine clinical use.

Islet amyloid polypeptide (IAPP) in patients with neuroendocrine tumours

Although IAPP was first discovered and isolated from amyloid deposits in an endocrine pancreatic tumour (EPT), surprisingly few reports have investigated the potential use of IAPP as a marker for neuroendocrine tumour growth. In this study we present results from plasma measurements of IAPP in 102 patients with neuroendocrine tumours. Four of 35 patients (11%) with midgut carcinoid tumours, but none of the patients (4 and 5, respectively) with lung carcinoids or with rectal carcinoids displayed elevated plasma levels of IAPP. Five of 31 patients (16%) with sporadic EPT and 3 of 27 patients (11%) with EPT and multiple endocrine neoplasia type 1 syndrome disclosed elevated IAPP levels. Within the different syndromes, 1/11 individuals with insulinoma, 2/16 with gastrinoma, 0/2 with glucagonoma, 0/3 with VIPoma and 5/26 with non-functioning tumours showed elevated plasma levels of IAPP. In two patients, the plasma IAPP levels were extremely elevated. These patients also exhibited altered glucose homeostasis. In response to a standardised mixed meal test, IAPP increased in parallel to the insulin, pancreatic polypeptide, gastrin and glucose responses. In MEN1 patients with hypercalcaemia due to increased secretion of parathyroid hormone, the plasma levels of IAPP were significantly higher before than after surgical removal of the parathyroid adenomas. However in normocalcaemic patients, no correlation between the blood calcium and plasma IAPP levels was found. Immunocytochemical staining of tumour tissue showed that 9/13 (69%) of insulin producing tumours, 4/14 (29%) of non-functioning tumours and 1/9 (11%) of gastrin producing tumours were IAPP immunoreactive. Amyloid deposits were always IAPP immunoreactive. In conclusion, increased circulating levels of IAPP occurred in 12% of 102 patients with neuroendocrine tumours. In 2 patients with extremely elevated plasma levels of IAPP, effects on glucose homeostasis were recorded. Thus, IAPP may be useful as an additional marker for neuroendocrine tumour growth in selected cases.

Extrapancreatic gastrinomas. Surgical experience

OBJECTIVE

Although widely reported on, the clinical diversity and eventual varied outcome of patients with extrapancreatic gastrinomas remain a medical mystery. In an attempt to help clarify conflicting management of extrapancreatic gastrinomas, we reviewed our experience with these unique tumors.

DESIGN

Retrospective analysis with long-term follow-up (mean, 8 years).

SETTING

Tertiary care referral center.

PATIENTS

From January 1958 through January 1993, we identified and operated on 23 patients with extrapancreatic gastrinomas (duodenum, n = 18; stomach, n = 3; nodal, n = 2). The 12 men and 11 women (none with multiple endocrine neoplasia type I syndrome) ranged in age from 12 to 68 years (mean, 47 years). Preoperatively, all patients were symptomatic with peptic ulcer disease (duodenal [n = 18, 78%], jejunal [n = 4, 17%]) and/or diarrhea (n = 17, 74%).

INTERVENTION

Preoperatively, tumor localization was successful in only three patients (13%). Surgical management included tumor excision only in 14 patients (61%), partial gastroduodenectomy in six (27%), total gastrectomy in one (4%), limited enterectomy in one (4%), and tumor biopsy alone in one (4%). Seven patients had evidence of lymphatic metastases at the time of operation, including a single patient with hepatic metastases (malignancy rate, 30%). Postoperatively, complications developed in seven patients (30%): wound infection in two, ileus in two, pulmonary sepsis in one, intra-abdominal abscess in one, and diabetic ketoacidosis in one. The postoperative mortality rate was 4%.

MAIN OUTCOME MEASURE

Emphasis was placed on rendering patients eugastrinemic.

RESULTS

Long-term follow-up (mean, 8 years) of all patients revealed that 11 patients (48%) were eugastrinemic, asymptomatic, and not receiving gastric acid-reducing medication. Sixteen patients remain alive and well. Of the six now decreased patients who had been participating in long-term follow-up (mean survival, 14 years), death was due to atherosclerotic coronary artery disease in four and tumor progression in two.

CONCLUSION

Following surgical excision, patients with extrapancreatic gastrinomas have a favorable outcome, with nearly half being cured.

Comparison of plasma pancreastatin and GAWK concentrations, presumed processing products of chromogranin A and B, in plasma of patients with pancreatic islet cell tumors

Plasma pancreastatin (PST) and GAWK, peptides processed from chromogranin A and B, were elevated in patients with various neuroendocrine tumors. In the present study, we measured plasma PST- and GAWK-like immunoreactivity (LI) concentrations in 12 patients with pancreatic islet cell tumors and evaluated them as a marker for these tumors. We also performed the gel filtration of the plasma from a gastrinoma patient and investigated the processing of PST and GAWK in plasma. Elevation of plasma PST-LI was found in 4 of 12 patients (33%) and elevation of plasma GAWK-LI was found in 6 of 12 patients (50%). A significant correlation was not found between plasma PST- and GAWK-LI concentrations of the patients. In the gel permeation chromatography of the plasma from a gastrinoma patient, PST-LI composed of a single peak but GAWK-LI composed of several components with wide range molecular weights.

Multiple endocrine neoplasm, type 1. Gastrinomas, pancreatic neoplasms, microcarcinoids, the Zollinger-Ellison syndrome, lymph nodes, and hepatic metastases

OBJECTIVE

We reviewed the age of presentation, malignant potential, and outcome of gastrinomas and pancreatic tumors in patients with multiple endocrine neoplasm, type 1.

DESIGN

Screening of one very large and one smaller, possibly related family on an island, including serum gastrin estimations and, when indicated, pancreatic ultrasound.

SETTING AND PATIENTS

Over 2000 family members and their family physicians were advised on screening procedures.

INTERVENTION

Data were collected and reviewed retrospectively and prospectively for all medical records, investigations, surgical procedures, and available tissue samples.

OUTCOME MEASUREMENTS

Criteria for diagnosis were established for radiological, biochemical, and histological studies.

RESULTS

Sixty-two patients had evidence of gastrinoma or pancreatic neoplasm. In 19 patients the diagnosis was based on demonstration of a tumor. In 21 patients the diagnosis was based on elevated serum gastrin concentration in the absence of demonstrable tumor. None of these patients required gastric surgery if they first underwent parathyroidectomy. In 18 patients the diagnosis was based on the combination of demonstrated pancreatic tumor plus elevated glucagon (two patients), gastrin (11 patients), or insulin (five patients) concentration. Peptic ulcer was difficult to control in seven of the 11 patients with elevated gastrin concentrations plus demonstrated tumor. Four patients had liver metastases that appeared to be secondary to the pancreatic gastrinoma. In patients with insulinomas, the first symptoms occurred before age 20 years. Elevated serum gastrin concentrations were not seen before age 24 years and were observed to occur for the first time in two patients after age 50 years.

Gastric endocrine cell evolution in patients with Zollinger-Ellison syndrome. Influence of gastrinoma growth and long-term omeprazole treatment

Evolution of gastrinoma tumoral mass, fasting serum gastrin concentrations, and gastric endocrine cells has been analyzed in 21 patients with the Zollinger-Ellison syndrome committed to long-term omeprazole treatment (up to 7.75 years, median 37 months). Gastrinoma growth was seen in eight patients. Significant increase in serum gastrin was only observed in the group of patients with gastrinoma growth. Fundic argyrophil cell densities were correlated with serum gastrin (r' = 0.68, P = 0.002). Argyrophil and antral gastrin cell densities significantly increased during the survey, but increases were greater in the group with gastrinoma growth (respectively, +136% and +131%) than in the other group (respectively, +34% and +43%). Progression in the degree of argyrophil cell hyperplasia, noted qualitatively, was observed in 11 patients. Fundic carcinoids developed in three of these 11 patients, all three having multiple endocrine neoplasia type 1 (MEN 1). Positive linear individual correlations (r > or = 0.85) between argyrophil cell densities and corresponding durations of omeprazole treatment were found in nine of the 10 patients studied at least three times and who had a clear-cut increase in those cell densities. Thus, increase in serum gastrin and fundic argyrophil cell densities appeared closely associated with gastrinoma growth; however, duration of drug-induced hypochlorhydria may also affect cell proliferation.

Interferon-alpha in the treatment of neuroendocrine tumours: effect on glucose tolerance and glucose-stimulated insulin secretion

OBJECTIVE

To find out whether long term treatment of neuroendocrine tumours with interferon-alpha has any effect on glucose metabolism or insulin secretion.

DESIGN

Open study.

SETTING

Department of Surgery, Lund University, Lund, Sweden.

SUBJECTS

Three women and two men, age range 47-72 years. One woman had a pancreatic gastrinoma, the others midgut carcinoids, and all had multiple liver metastases.

INTERVENTIONS

Intravenous and oral glucose challenges (separated by at least a week) before treatment, and then yearly for three years.

MAIN OUTCOME MEASURES

Changes in plasma insulin and blood glucose concentrations.

RESULTS

Neither the basal concentrations of plasma insulin or blood glucose nor the responses to the glucose challenges changed during the three year period.

CONCLUSION

Long term treatment with interferon-alpha has no obvious adverse effects on glucose tolerance or insulin secretion.

Islet amyloid polypeptide-like immunoreactivity in human tissue and endocrine tumors

We have detected islet amyloid polypeptide (IAPP)-like immunoreactivity (-LI) in human pancreas and in a range of endocrine tumors, including oat cell carcinoma of the lung and pancreatic tumours producing insulin, gastrin, glucagon, and vasoactive intestinal peptide. Gel permeation chromatography of the IAPP-LI revealed that, except in the carcinoid, more than 80% coeluted with synthetic human IAPP. The remaining immunoreactivity consisted of variable amounts of larger and smaller molecular forms. The concentration of IAPP-LI in the circulation of patients with diagnosed pancreatic endocrine tumors was not significantly elevated above normal fasting levels. IAPP is, therefore, produced by a range of endocrine tumors and may relate to the deposition of endocrine amyloid.

Chromogranin A and pancreastatin-like immunoreactivity in serum of gastrinoma patients

Gastrin and pancreastatin-like immunoreactivity were determined by radioimmunoassay methods and chromogranin A was determined by enzyme-linked immunoassay in sera from 18 patients with gastrinomas (Zollinger-Ellison syndrome) and in 20 age and sex matched controls. Gastrin serum levels in the gastrinoma patients were in the range 26-80,000 pmol/l, and in the controls 5-31 pmol/l. Chromogranin A serum levels in the gastrinoma group were in the range 6-2,700 ng/ml (mean +/- SEM: 400 +/- 147 ng/ml). The mean value of chromogranin A was significantly higher than in the control group (8 +/- 2 ng/ml, p = 0.008). The serum levels of pancreastatin-like immunoreactivity in the gastrinoma patients were in the range 23-1,994 pg/ml (597 +/- 123 pg/ml). The mean value of pancreastatin-like immunoreactivity in the gastrinoma group was significantly higher than in the control group (104 +/- 25 pg/ml, p = 0.0002). The levels of chromogranin A and pancreastatin-like immunoreactivity were significantly higher in patients with verified metastatic disease (p = 0.04, p = 0.01 respectively). There was a significantly positive correlation between levels of gastrin and pancreastatin-like immunoreactivity (r = 0.7, p = 0.002), while no correlation was found between gastrin and chromogranin A levels or between levels of chromogranin A and pancreastatin-like immunoreactivity. The study demonstrates an elevation of both chromogranin A and pancreastatin-like immunoreactivity in serum of gastrinoma patients. The lack of correlation between gastrin and chromogranin A, however, gives an indication that the gastrinoma cells are not the main source of serum chromogranin A elevation.

[Pancreatic endocrine tumor with metastases and increase of alpha-fetoprotein. A case report]

The authors report the case of a 48 years old man presenting a pancreatic islet cell carcinoma (gastrinoma) with liver, nodes and peritoneal metastases, associated with an elevated alpha-fetoprotein (AFP) concentration. Incomplete remission was first obtained with a chemotherapy using Streptozotocin combined with 5-Fluorouracil, in association with a Somatostatin analogue (SMS 201-995). But when relapses occur, another chemotherapy was not so effective. Serum gastrin and AFP levels had the same evolution and appear to have the same interest to follow the course of the disease.

Primary extrapancreatic gastrinoma

Extrapancreatic gastrinoma is a rare clinical entity encountered in surgical practice. A patient was referred to us who had a history of recurring symptoms of peptic ulcer disease and ulcer perforation located at an unusual site. Serum gastrin levels were abnormally high. Scopy revealed multiple ulcers in the antrum and duodenum. A mass superior to the head of the pancreas was detected on USG, which later on found to be a separate mass on CT scan. The tumour was excised and confirmed on histopathology. Results of conservative surgery were found to be satisfactory.

[Use of octreotide in the treatment of digestive endocrine tumors. A French multicenter study]

Morbidity and mortality in endocrine gastro-enteropancreatic (GEP) tumours are mainly related to the clinical consequences of tumoral peptide hypersecretion. Surgical resection at an early stage is the only curative treatment. However, most tumours are detected only when the hypersecretory state reflects the presence of metastases; surgery and chemotherapy then give only palliative results counterbalanced by serious side-effects. Somatostatin inhibits most endocrine secretions of the GEP tract and thus can alleviate invalidating symptoms. Its use is limited by its short half-life (2 min), the necessity of i.v. infusion and the possibility of a rebound phenomenon. Octreotide, a synthetic somatostatin analogue with a long duration of action, is administered subcutaneously and allows ambulatory treatment. In our series of 78 patients we observed about 80 percent of excellent or good clinical results, enabling the patients to resume normal life. Only minor and transient side-effects were noted. The overall tolerance of the drug was considered excellent or good. Prolonged administration of octreotide is a safe and effective symptomatic treatment in patients without any restriction of anti-tumoral procedures. Furthermore, it prevents the severe carcinoid crises that occur during surgery or embolization in patients with carcinoid syndromes.

7B2, a possible marker for nonfunctioning pancreatic islet cell tumor

Plasma 7B2 was measured in 13 patients with pancreatic islet cell tumors, 11 with pancreatic adenocarcinoma and 31 normal subjects as a control. The mean (+/- SD) concentrations of plasma 7B2 in the normal subjects and the patients with pancreatic islet cell tumors were 67 +/- 10 and 1041 +/- 1786 pmol/l, respectively, and the value in the patients with pancreatic islet cell tumors was significantly higher than that in the normal subjects (p less than 0.01). Elevation of plasma 7B2 over the normal range, defined as less than the mean + 3SD value of those in the normal subjects, was found in 10 of 13 patients with pancreatic islet cell tumors including 4 with nonfunctioning tumor. Plasma 7B2 dropped into the normal range postoperatively in 3 patients with nonfunctioning tumor. Plasma 7B2 concentrations in the patients with pancreatic adenocarcinoma remained in the normal range. These results raise a possibility that 7B2 is a useful marker for pancreatic islet cell tumors, in particular nonfunctioning tumor.

Natural killer cell activity in patients with neuroendocrine tumours of the gastrointestinal tract; relation with circulating gastrointestinal hormones

We have evaluated the peripheral blood natural killer (NK) cell activity and the in vitro effect of recombinant gamma-interferon (r gamma-IFN) on NK cell activity in 23 patients with a neuroendocrine tumour of the pancreas, small intestine or liver, and 23 healthy controls. Patients with a gastrinoma showed a NK cell activity which was not different from that of the control group, whereas patients with another type of neuroendocrine tumour had a decreased NK cell activity compared to the controls (p less than 0.05) and the gastrinoma patients (p less than 0.02). The impaired NK cell activity in these patients was as such not related to the presence of liver metastasis or performance status of the patients. r gamma-IFN significantly stimulated the NK cell activity in patients and controls. However, the cytotoxic response of the patients with a hormone production other than gastrin remained lower than in the two other groups. Follow-up studies in 8 patients showed NK cell activities not to vary with stable disease, to decrease with progressive disease, and to increase with regression of disease. In conclusion, NK cell activity is suppressed in patients with neuroendocrine tumours that produce hormones other than gastrin. This impairment is not related to the presence of metastasis but seems to be related to the course of the disease.

Processing-independent analysis (PIA)--a new diagnostic tool

Posttranslational processing is an important phase of the expression of most eucaryotic genes in terms of functional proteins. Among these, secretory proteins and peptides are of particular interest for clinical chemists, since diagnostic measurements of circulating proteins and peptides constitute a major discipline in clinical chemistry. The posttranslational covalent maturation of secretory proteins and peptides involves multiple enzymatic modifications of the corresponding proproteins along the intracellular secretory pathway. During the eighties, an increasing amount of evidence has indicated that sick secretory cells fail to process their secretory products normally. The diseased cells therefore fail to process their secretory products normally. The diseased cells therefore release also incompletely processed precursors and processing-intermediates. In order to measure the degree of disease, assays that measure proteins and peptides independent of the degree of processing are therefore desirable. We have now designed a new analytical principle, according to which secretory proteins, peptides and their precursors can be accurately quantitated irrespective of the degree of processing. This principle, named processing-independent analysis (PIA), is generally applicable to all cellular synthesized substances. The principle has been applied to and developed first for a well-defined secretory peptide system, progastrin and its products. Using this model, the results obtained so far confirm the diagnostic superiority of processing-independent analysis in comparison with conventional assays for bioactive peptides.

Selective arterial stimulation of secretin in localization of gastrinomas

In two patients with malignant gastrinoma and the Zollinger-Ellison syndrome, we were able to use selective arterial stimulation with secretin as a technique to localize the lesions accurately, allowing resection. The technique of selected arterial secretin stimulation is one of measuring variations in gastrin levels in both the hepatic vein and a peripheral artery at specified times after injection of secretin into a specific artery. When the criteria for localization have been met, one can plot the presence of the gastrinoma within the blood supply of the injected artery and, using angiograms, thus accurately localize the lesion. This method promises to be a valuable additional tumor-localizing procedure, particularly when gastrinomas are extrapancreatic.

Source of plasma chromogranin A elevation in gastrinoma patients

Chromogranin A (Cg A) is a protein that is coreleased with peptide hormones from gut endocrine cells and tumors. Plasma levels of Cg A, pepsinogen group I, and gastrin were measured in 31 patients with gastrinoma. Mean Cg A level in 10 patients with gastrinoma who were not operated on was 169 +/- 32 ng/mL, while in 9 control patients it was 28 +/- 5 ng/mL. In 18 patients with gastrinoma with residual tumor after total gastrectomy, the mean Cg A level was 45 +/- 6 ng/mL, and in 10 patients with normal gastrin levels after total gastrectomy and tumor excision, the mean Cg A level was 40 +/- 4 ng/mL. In 7 patients in whom pregastrectomy and postgastrectomy Cg A levels were measured, the mean reduction was 94 +/- 27 ng/mL, or 66%. There was no correlation between Cg A levels and amount of tumor, presence of metastases, or multiple endocrine neoplasia type I syndrome. There was a significant correlation between Cg A and pepsinogen I levels but no correlation between Cg A and gastrin levels. The results suggest that the elevated plasma Cg A levels in patients with gastrinoma are determined primarily by the trophic effects of gastrin on gastric enterochromaffinlike cells rather than by corelease from the gastrin-producing tumor itself.

Zollinger-Ellison syndrome in a patient with normal screening gastrin level

A 59-year-old female presented with multifocal peptic ulcer disease and diarrhea. A fasting serum gastrin level obtained while the patient was receiving no antacid therapy was normal. A secretin stimulation test was positive. A small gastrinoma was found in the anterior duodenal wall at exploratory laparotomy. Normal fasting gastrin levels do occur in patients with overt Zollinger-Ellison syndrome and should not deter further investigation if clinical suspicion of this syndrome is high.

Selective surgical management of correctable hypergastrinemia

Sixty patients with surgically correctable hypergastrinemia were treated between 1960 and 1988. Provocative testing was used when available to select appropriate operations. Sources of hypergastrinemia included antral G cell hyperplasia (AGCH) (17), pancreatic gastrinomas (14), duodenal gastrinomas (11), multiple gastrinomas in patients with type I multiple endocrine neoplasia (MEN I) (five), lymph node gastrinomas (four), and the source not found in nine patients. Eugastrinemia was achieved by resection in 17 of 17 patients with AGCH, nine of 11 patients with duodenal gastrinomas, three of four patients with lymph node gastrinomas, zero of 14 patients with pancreatic gastrinomas, zero of five patients with MEN I, and zero of nine patients in whom the source was not found. Hepatic metastases developed in 11 patients with pancreatic gastrinomas, two patients with MEN I, one patient with duodenal gastrinomas, and one patient with lymph node gastrinomas. One patient in whom the source of the hypergastrinemia was not found developed hepatic metastases, and seven required total gastrectomy. This experience suggests the following: (1) that patients with AGCH, duodenal gastrinomas, or lymph node gastrinomas can usually be rendered eugastrinemic by resection; (2) that patients with pancreatic gastrinomas, whether sporadic or familial (MEN I), are rarely cured by resection and frequently develop hepatic metastases; and (3) that patients in whom the source of the hypergastrinemia is not identified and removed frequently require total gastrectomy, but antroduodenectomy should be considered because it may uncover an occult duodenal microneurogastrinoma or may correct AGCH.

Effects of sandostatin on plasma chromogranin-A levels in neuroendocrine tumors

We have determined the effects of Sandostatin (SMS 201-995, Sandoz) on chromogranin-A (CgA) in the blood of 14 patients with neuroendocrine tumors of the gastroenteropancreatic axis, 7 with carcinoid tumors, 5 with gastrinomas, and 1 each with a glucagonoma and tumor-secreting vasoactive intestinal peptide. Two thirds of the patients had elevated plasma CgA. Sandostatin administration suppressed CgA in 12 of the 14 patients. In 8 of 10, the clinical response to Sandostatin paralleled the reduction in CgA levels. There was a strong correlation between the change in CgA levels and the respective blood concentration of the hormone produced by the tumor. Serial measurement of CgA may provide an additional means of monitoring these tumors and their secretory activity where other measures are not available.

A new pituitary protein 7B2 is increased in patients with high alpha- or beta-hCG

The presence of 7B2 (a 180 amino acid peptide first extracted from the porcine pituitary) was investigated by a specific radioimmunoassay and gel filtration chromatography in the plasma of three groups of patients known to have increased levels of alpha- and beta-hCG subunits. Plasma 7B2 immunoreactive equivalents (7B2-IE) were increased in postmenopausal women (range 67-143 pmol/l, median: 94 pmol/l, N = 20, P less than 0.05), in patients with Klinefelter's syndrome (range 195-230 pmol/l), median 213 pmol/l, N = 4, P less than 0.01) and in 17 patients with malignant endocrine gastrointestinal tumours (range 66-20,000 pmol/l, N = 32) compared with healthy controls (range 23.6-98.2 pmol/l, median 41.5 pmol/l, N = 40). Tumour tissue from 4 patients with endocrine pancreatic tumours had significantly higher 7B2-IE concentrations than normal pancreatic tissue, with the highest concentration in an insulinoma (449 pmol/g, normal: 28 pmol/g). During therapy almost parallel changes in plasma 7B2 and other hormones were noted and 7B2-IE therefore might be an additional marker for cancers of the APUD system.