Screening for multiple endocrine neoplasia type I and hormonal production in apparently sporadic neuroendocrine tumors

Screening was performed in 130 consecutive patients with apparently sporadic neuroendocrine tumors (NET) to assess the prevalence of multiple endocrine neoplasia type 1 (MEN1) and hormonal production. Screening for MEN1 included measurement of serum calcium and PTH [PTH-(1-84)], gastrin, PRL, and insulin-like growth factor type I (IGF-I) levels. MEN1 genetic testing was performed in patients with two components of the MEN1 syndrome. Screening for hormonal production included measurement of serum neuron-specific enolase (NSE), calcitonin (CT), glycoprotein α-subunit (GPα), hCG β-subunit (free hCGβ), and somatostatin levels. Twenty-four-hour urinary free cortisol (UFC) and 5-hydroxyindolacetic acid (5-HIAA) determinations were also performed. Four patients had hyperparathyroidism, none of whom had pituitary or familial disease. Hyperprolactinemia was compatible with a pituitary disease in one patient. No acromegalic feature or any increase in IGF-I was found. Hypergastrinemia, compatible with an associated pancreatic NET, was found in one patient. Genetic screening of the MEN1 gene was performed in five of the six patients with two components of the MEN1 syndrome. A nonsense mutation (Arg¹⁰⁸ stop) was identified in the tumor of one patient. Elevated NSE, 5- HIAA, CT, GPα, free hCGβ, SMS, and nonsuppressible UFC were found in 47%, 46%, 14%, 19%, 12%, 3%, and 6% of NET patients, respectively. Production of CT, GPα, and free hCGβ was highly related to the primary site: all but two of these secretions originated in foregut NET. 5-HIAA secretion was found in 27% of foregut-derived and 85% of midgut-derived NET. In conclusion, MEN1 is a rare event in patients presenting with apparently sporadic NET. It occurred mainly in foregut NET and should be screened for by serum calcium and PTH- (1-84) measurements. Routine hormonal measurements should depend on the primary site. NSE, 5-HIAA, CT, and αGP should be routinely measured in foregut-derived NET; only serum NSE and 5-HIAA measurements are recommended in midgut-derived NET.