Octreotide lar affects the volume of pituitary adenoma in acromegalic patients.

Introduction: We studied changes of pituitary adenoma volumes in patients treated with octreotide LAR (SSLAR) over 12 months prior to surgery.

Materials And Methods: 26 patients (22 female and 4 male, mean age 57.5±15.0 years) were treated with SSLAR: 5 patients with microadenoma - during 6 months, and 21 patients with macroadenoma - during 12 months before surgery. Concentration of hGH and IGF-1 was evaluated at 0, 3, 6 and 12 months, while MRI images were taken at 0, 6 and 12 months prior to surgery. The volume of pituitary adenoma, estimated as that of an ellipsoid, was based on MRI image projections. Basic statistics, Shapiro-Wilk and Wilcoxon tests were applied.

Results: Median values of hGH and IGF-1 concentrations prior to treatment were 19.0 ng/ml (IQR=40.7) and 766.4 ng/ml (IQR=787.7), respectively. After 6 and 12 months the median value of hGH concentration decreased to 6.3 ng/ml (IQR=9.0) and 3.45 ng/ml (IQR=3.7), respectively, while the median values of IGF-1 became 535.0 ng/ml (IQR=652.8) and 287.0 (IQR=275.7), respectively. All differences were statistically significant (p<0.05) as compared to basal value. The median volumes of adenomas differed significantly and were estimated at: 1.1 cm (3) (IQR=2.5) prior to treatment, 0.5 cm (3) (IQR=1.5) after 6 months, and 0.35 cm (3) (IQR=2.4) after 12 months of SSLAR administration.

Conclusion: Treatment of acromegalic patients with somatostatin analogues not only decreases the concentration of hGH and IGF-1, but also appears to decrease the size of the tumour in about 50% of patients treated, leading to general enhancement of the outcome of surgery.