Carcinoid tumors--somatostatine in the diagnosis and therapy.

Background: Carcinoid tumors have a neuroendocrine origin and endocrine activity is typical for them.

Objectives: The main objective of the present study was to determine differences in the levels of an endogenous somatostatin, a neuron specific enolase in serum and excretion of 5-HIAA in the urine in patients with carcinoid tumors and also to determine the changes of these parameters during the treatment with long acting somatostatin analogue--lanreotide.

Subjects And Methods: 30 pts with carcinoid tumors (20 pts with metastatic disease, 10 pts after resection of the primary tumor without known metastases at the time of the investigation) and 12 healthy probands were included in the study. Circadian rhythm of endogenous somatostatin in all groups was performed. Levels of neuron specific enolase in the serum and the excretion of 5-HIAA in the urine in pts with carcinoid tumors were done. The estimation of these parameters were repeated in the group of pts with advanced metastatic disease during the treatment with the lanreotide.

Results: We confirmed the existence of the circadian rhythm of endogenous somatostatin in all groups. Chronogram of somatostatin in pts without known metastases shows the same characteristics as the chronogram of healthy volunteers. The chronogram of pts with metastatic carcinoid disease shows a statistically significant differences in comparison with healthy volunteers--higher mesor and later acrophase of 24-hour rhythm (p < 0.05). During the therapy with lanreotide lower mesor was observed (p < 0.05). The amount of the 5-hydroxyindolacetate acid in urine in pts with metastatic carcinoid was statistically significant higher than in the pts without metastases (p < 0.001). During therapy with the lanreotide the decrease in the 5-HIAA in the urine (p < 0.05) was observed. Neuron specific enolase in the serum was higher in group with the metastatic disease (p < 0.001).

Conclusion: Abnormalities in the somatostatin secretion and the concentration of the neuron specific enolase in serum are useful markers for the differential diagnosis and might distinguish the carcinoid patients with and without metastases. Urine excretion of 5-HIAA is a good marker of endocrine activity of the carcinoid tumor. (Fig. 4, Tab. 3, Ref. 22.)