Octreotide lar affects the volume of pituitary adenoma in acromegalic patients

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

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.

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.

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.