Endocrine Abstracts

Introduction: Surgery remains the first-line treatment of clinically non-functioning pituitary adenomas (NFPA). However, the presence of somatostatin receptors (SSTR) in these tumours forms the basis of clinical use of somatostatin analogues (SSA). Visualisation of SSTR in scintigraphy is compulsory to introduce SSA therapy in NFPA.

Aim: To assess the effectiveness of long-term somatostatin analogues treatment on tumour volume and visual field in patients with NFPA.

Material and methods: Twenty five patients with diagnosed NFPA and strong expression of SSTR in scintigraphy were enrolled in the study. Patients were divided into 2 subgroups: subgroup A, which comprises 8 patients treated with SSA in primary therapy and subgroup B including 17 patients treated with SSA after incomplete surgery. All patients received octreotide LAR 20 mg or lanreotide 120 mg every four weeks and the duration of therapy varied from 7 months to 14 years. Patient’s condition, tumour size, visual field and undesirable effects were evaluated in the study.

Results: Almost 70% of patients felt clinical improvement in headaches, which occurred less frequently and were less intense. Stabilisation of tumour size was achieved in 60% of patients. Reduction of tumour volume was only observed in patients treated with SSA as adjuvant therapy after incomplete surgery (23.5% of subgroup B). Adenoma shrinkage was not always associated with improvement in the visual field. Tumour progression was noted with similar frequency in both subgroups (25% subgroup A vs. 23.5% subgroup B). Tumour enlargement correlated with deterioration of visual field. Moreover, an increase of adenoma size was observed within first 2 years of the therapy, while tumour shrinkage occurred 3–5 years after introduction of SSA treatment. SSA were well-tolerated and only four patients developed asymptomatic cholelithiasis during the pharmacotherapy.

Conclusion: SSA are effective in both primary and secondary therapy of NFPA. Long-term treatment with SSA results in stabilisation of tumour size in the majority of cases. SSA therapy should be considered in postoperative treatment of NFPA as tumour shrinkage may be observed in some cases.