Endocrine Abstracts

Clinically non-functioning pituitary adenomas (CNFPA) represent a heterogenous group of tumors. Most of CNFPA are aggressive, usually diagnosed relatively late and surgery often fails to achieve the complete excision of tumor and the recurrence rate is high. About 80% of CNFPA are characterized by intense expression of somatostatin receptors (SSTR) inspiring use of somatostatin analogs (SSTa) in the medical cure of CNFPA. Scintigraphy with visualization of SSTR2 expression and/or immunohistochemistry with selective recognition of all five SSTR subtypes are used for justify the long-acting SSTa treatment of CNFPA.

The aim of the study was to correlate the expression of SSTR determined with immunohistochemistry or receptor scintigraphy techniques (group of 48 patients) and verify effects of long-acting SSTa in the treatment of CNFPA (11 patients).

Results: All 11 patients with CNFPA treated with SSTa indicated expression of SSTR2 in immunohistochemistry but only nine patients of this group were SSTR2 positive in scintigraphy. Absence of SSTR2 expression in scintigraphy was not always associated with absence of SSTR2 visualization in immunohistochemistry. Intense expression of SSTR1 and SSTR5 was observed in most CNFPA. In all patients treated with SSTa stabilization of the tumor growth and stabilization or improvement of visual disturbances were observed.

Conclusion: Both scintigraphy and immunohistochemistry methods must be combined to assess the presence of SSTR in CNFPA. The treatment of CNFPA with SSTa is connected with the positive effect on tumor size progression – stabilize the tumor mass. SSTR1 and SSTR5 expression in CNFPA justifies the trials to treatment CNFPA with broad spectrum SSTa, like SOM230.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.