Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2006) 11 P611

ECE2006 Poster Presentations Neuroendocrinology and behaviour (70 abstracts)

Octreotide shrinks the cellular rather than the vascular compartment in acromegalic tumours in vivo

AM Manuchehri 1 , M Lowry 1 , C Rowland Hill 3 , LW Turnbull 2 & SL Atkin 2


1University of Hull, Hull, East Yorkshire, United Kingdom; 2Hull York Medical School, Hull, East Yorkshire, United Kingdom; 3Hull & East Yorks NHS, Hull, East Yorkshire, United Kingdom.


Rationale: Octreotide is known to shrink acromegalic tumours in vivo. However, the mechanism for this is unclear. To investigate the mechanism of shrinkage we used dynamic contrast enhanced MR imaging (DCE-MRI) to visualise the vascular components within the somatotroph adenomas.

Subjects & Methods: Six patients with confirmed acromegaly comprising 4 microadenomas (all male) and 2 macroadenomas (1 male, 1 female) were recruited. All patients were treated with 3 times daily subcutaneous octreotide for a 24-week period. Then all but one microadenoma were treated with monthly Sandostatin LAR for a further 24 weeks. All patients underwent growth hormone day curves at the beginning, 24 weeks and at 48 weeks. DCE-MRI was performed at 0, 24 and 48 weeks. The data was analysed using a two compartment model, providing an estimate of vascular permeability and contrast distribution volume. Study was approved by local ethics committee.

Results: All but one macroadenoma achieved a medical cure with a mean growth hormone of less than 5 mU/l at 24 and 48 weeks. In the microadenomas, tumour size decreased by 55% (at 24 weeks for the microadenoma that stopped treatment), 59%, 70% and 83% at 48 weeks. In the macroadenomas, tumour size decreased by 2% and 80% at 48 weeks. Mean maximal enhancement and gadolinium exchange rate, a measure of tumour vascularity, did not differ before and after octreotide treatment (ME 96±36 vs 117±28 respectively; ExCH 662±352 vs 420±393, respectively; P<0.05). Distribution volume, which is a measure of extracellular volume, increased significantly by 62% before and after octreotide therapy (95±58 vs 154±81, respectively, P<0.028).

Conclusion: The shrinkage of acromegalic tumours by octreotide is either due to a direct reduction in cell volume or a reduction in cell number, but not due to a reduction in tumour vascularity.

Volume 11

8th European Congress of Endocrinology incorporating the British Endocrine Societies

European Society of Endocrinology 
British Endocrine Societies 

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