Endocrine Abstracts

Objective: It is still unknown how pituitary adenomas grow over years and whether growth kinetics follow a distinct growth model. Definition of adenoma growth kinetics would substantially enhance knowledge of biological behaviour. The objective of this study was to define a growth model for non-functioning pituitary adenomas.

Methods: Fifteen patients who had five or more serial high-quality examinations with magnetic resonance images or computerized tomography scans were detected among 216 surgical cases with non-functioning pituitary adenomas. Tumour volumes were assessed using a stereological method based on the Cavalieri principle. Tumour growth during the observation period was analyzed and different growth models were fitted to the data.

Results: Fifteen pituitary adenomas (3 newly diagnosed tumours and 12 recurrent tumours) had been longitudinally observed during a median observation period of 7.4 years (range 2.3–11.9 years). Growth kinetics could be described either by an exponential growth model (nine patients) or by a logistic model (five patients). One tumour remained nearly unchanged in size during the observation period. None of the adenomas showed accelerated growth during the observation period. The mean tumour volume doubling time for the 14 growing adenomas was 3.1 years (range: 0.8–27.2 years).

Conclusions: Growth of pituitary adenomas can be described by distinct growth models. Understanding of biological behaviour is important to optimize patient management, develop treatment algorithms and establish follow-up protocols.