Influence of GH substitution therapy in deficient adults on the recurrence rate of hormonally inactive pituitary adenomas:: a case-control study

Objective: Several studies documented metabolic and psychological benefits of GH substitution in deficient adults, most of them suffering from benign pituitary adenomas. Since GH substitution is considered to promote tumour regrowth, adequate treatment is performed with some reservation. Therefore, we aimed to elucidate the effect of GH replacement therapy on tumour recurrence following surgery. Methods: In patients with hormonally inactive pituitary adenomas undergoing tumour surgery, a retrospective case-control study was performed. Pre- and postoperative magnetic resonance (MR) images of GH-treated and untreated patients were matched for best fit by two independent observers. The treated patients were retrieved from the surveillance programme of the German KIMS database and the untreated from the database of the Department of Neurosurgery, University of Erlangen. A total of 55 matched pairs were followed for at least 5 years. Tumour recurrence and progression rates were determined according to the postoperative MR. Results: There were 16 tumour progressions in the treatment group and 12 in the control group. Statistical analysis revealed no significant increase in either recurrence (P=0.317) or progression (P=0.61.7) within the follow-up period of 5 years when GH was adequately replaced. Conclusions: This study provides further observational data of substitution therapy in GH-deficient adults with pituitary adenomas. Comparing long-term surgical results, we found no evidence that GH substitution should be withheld in deficient patients. Even residual tumour does not constitute a contraindication to GH replacement. However, since pituitary tumours are slow growing, an observational period of 5 years may not have been long enough to verify any absolute influence oil recurrence potential.