Endocrine Abstracts

Background: Treatment of patients with acromegaly caused by pituitary adenoma with somatostatin analogues leads to significant tumour shrinkage in 23–73% of the cases. Although not widely accepted, it has been suggested that the surgical remission rate may be improved by pre-operative treatment with these agents.

Aim: To assess whether the degree of tumour shrinkage by lanreotide offered pre-operatively affects the surgical success in acromegalics with pituitary macroadenoma.

Patients and methods: Nineteen subjects with active acromegaly (mean GH in GHDC: median 70.0 mU/L; range 11.6–104 – all with high IGF-I) attributed to pituitary macroadenoma were studied prospectively. All had lanreotide for 16 weeks pre-operatively (initially 30 mg/2 weeks and from week 8, if mean GH>5 mU/L, 30 mg/week). Pituitary MRI was performed before entry and at a median interval 12.5 (range 8.6–15.7) weeks later. The surgical outcome was assessed by OGTT and IGF-I 18 weeks post-operatively (off lanreotide).

Results: All but one subjects, showed significant reduction of the adenoma volume (median 33.1%; range 6.4–64.9%). Invasion to sinus(es) was not altered (42% of subjects). Nadir GH<2 mU/L in OGTT was achieved in 11/19 (57.9%) of patients post-operatively. There was no correlation between mean GH at entry and percentage of tumour shrinkage. There was no difference in the tumour volume at entry or in the tumour volume after treatment with lanreotide or in the tumour shrinkage between those achieving or not achieving nadir GH<2 mU/L in OGTT, as well as between those achieving or not achieving normal IGF-I post-operatively. There was a difference in the mean GH at entry between those achieving or not achieving nadir GH<2 mU/L in OGTT (median 29.7 vs 101.7; range 11.6–104 vs 26.5–104; P=0.02).

Conclusion: The degree of tumour shrinkage by pre-operative treatment with lanreotide does not affect the surgical success rate in patients with acromegaly caused by macroadenoma.